Batteries comprising alkali-transition metal phosphates and preferred electrolytes

ABSTRACT

A secondary electrochemical cell is described having (a) a first electrode comprising an active material of the formula Li a Co e Fe f M 1   g M 2   h M 3   i XY 4 , (b) a second electrode which is a counter-electrode to said first electrode; and (c) an electrolyte comprising an electrolyte salt, a cyclic ester and a carbonate selected from the group consisting of alkyl carbonates, alkylene carbonates, and mixtures thereof.

This application is a divisional of application Ser. No. 10/116,276filed Apr. 3, 2002, pending.

FIELD OF THE INVENTION

This invention relates to batteries. In particular, this inventionrelates to batteries comprising active materials comprising lithium orother alkali metals, transition metals, and phosphates or similarmoieties, with electrolytes comprising alkylene carbonates and cyclicesters.

BACKGROUND OF THE INVENTION

A wide variety of electrochemical cells, or “batteries,” is known in theart. In general, batteries are devices that convert chemical energy intoelectrical energy, by means of an electrochemical oxidation-reductionreaction. Batteries are used in a wide variety of applications,particularly as a power source for devices that cannot practicably bepowered by centralized power generation sources (e.g., by commercialpower plants using utility transmission lines).

Batteries can be generally described as comprising three components: ananode that contains a material that is oxidized (yields electrons)during discharge of the battery (i.e., while it is providing power); acathode that contains a material that is reduced (accepts electrons)during discharge of the battery; and an electrolyte that provides fortransfer of ions between the cathode and anode. During discharge, theanode is the negative pole of the battery, and the cathode is thepositive pole. Batteries can be more specifically characterized by thespecific materials that make up each of these three components.Selection of these components can yield batteries having specificvoltage and discharge characteristics that can be optimized forparticular applications.

Batteries can also be generally categorized as being “primary,” wherethe electrochemical reaction is essentially irreversible, so that thebattery becomes unusable once discharged; and “secondary,” where theelectrochemical reaction is, at least in part, reversible so that thebattery can be “recharged” and used more than once. Secondary batteriesare increasingly used in many applications, because of their convenience(particularly in applications where replacing batteries can bedifficult), reduced cost (by reducing the need for replacement), andenvironmental benefits (by reducing the waste from battery disposal).

There are a variety of secondary battery systems known in the art. Amongthe most common systems are lead-acid, nickel-cadmium, nickel-zinc,nickel-iron, silver oxide, nickel metal hydride, rechargeablezinc-manganese dioxide, zinc-bromide, metal-air, and lithium batteries.Systems containing lithium and sodium afford many potential benefits,because these metals are light in weight, while possessing high standardpotentials. For a variety of reasons, lithium batteries are, inparticular, commercially attractive because of their high energydensity, higher cell voltages, and long shelf-life.

Lithium batteries are prepared from one or more lithium electrochemicalcells containing electrochemically active (electroactive) materials.Among such batteries are those having metallic lithium anodes and metalchalcogenide (oxide) cathodes, typically referred to as “lithium metal”batteries. The electrolyte typically comprises a salt of lithiumdissolved in one or more solvents, typically nonaqueous aprotic organicsolvents. Other electrolytes are solid electrolytes (typically polymericmatrixes) that contain an ionic conductive medium (typically a lithiumcontaining salt dissolved in organic solvents) in combination with apolymer that itself may be ionically conductive but electricallyinsulating.

Cells having a metallic lithium anode and metal chalcogenide cathode arecharged in an initial condition. During discharge, lithium metal yieldselectrons to an external electrical circuit at the anode. Positivelycharged ions are created that pass through the electrolyte to theelectrochemically active (electroactive) material of the cathode. Theelectrons from the anode pass through the external circuit, powering thedevice, and return to the cathode.

Another lithium battery uses an “insertion anode” rather than lithiummetal, and is typically referred to as a “lithium ion” battery.Insertion or “intercalation” electrodes contain materials having alattice structure into which an ion can be inserted and subsequentlyextracted. Rather than chemically altering the intercalation material,the ions slightly expand the internal lattice lengths of the compoundwithout extensive bond breakage or atomic reorganization. Insertionanodes contain, for example, lithium metal chalcogenide, lithium metaloxide, or carbon materials such as coke and graphite. These negativeelectrodes are used with lithium-containing insertion cathodes. In theirinitial condition, the cells are not charged, since the anode does notcontain a source of cations. Thus, before use, such cells must becharged in order to transfer cations (lithium) to the anode from thecathode. During discharge the lithium is then transferred from the anodeback to the cathode. During subsequent recharge, the lithium is againtransferred back to the anode where it reinserts. This back-and-forthtransport of lithium ions (Li+) between the anode and cathode duringcharge and discharge cycles had led to these cells as being called“rocking chair” batteries.

A variety of materials have been suggested for use as cathode activematerials in lithium batteries. Such materials include, for example,MoS₂, MnO₂, TiS₂, NbSe₃, LiCoO₂, LiNiO₂, LiMn₂O₄, V₆O₁₃, V₂O₅, SO₂,CuCl₂. Transition metal oxides, such as those of the general formulaLi_(x)M₂O_(y), are among those materials preferred in such batterieshaving intercalation electrodes. Other materials include lithiumtransition metal phosphates, such as LiFePO₄, and Li₃V₂(PO₄)₃. Suchmaterials having structures similar to olivine or NASICON materials areamong those known in the art. Cathode active materials among those knownin the art are disclosed in S. Hossain, “Rechargeable Lithium Batteries(Ambient Temperature),” Handbook of Batteries, 2d ed., Chapter 36,Mc-Graw Hill (1995); U.S. Pat. No. 4,194,062, Carides, et al., issuedMar. 18, 1980; U.S. Pat. No. 4,464,447, Lazzari, et al., issued Aug. 7,1984; U.S. Pat. No. 5,028,500, Fong et al., issued Jul. 2, 1991; U.S.Pat. No. 5,130,211, Wilkinson, et al., issued Jul. 14, 1992; U.S. Pat.No. 5,418,090, Koksbang et al., issued May 23, 1995; U.S. Pat. No.5,514,490, Chen et al., issued May 7, 1996; U.S. Pat. No. 5,538,814,Kamauchi et al., issued Jul. 23, 1996; U.S. Pat. No. 5,695,893, Arai, etal., issued Dec. 9, 1997; U.S. Pat. No. 5,804,335, Kamauchi, et al.,issued Sep. 8, 1998; U.S. Pat. No. 5,871,866, Barker et al., issued Feb.16, 1999; U.S. Pat. No. 5,910,382, Goodenough, et al., issued Jun. 8,1999; PCT Publication WO/00/31812, Barker, et al., published Jun. 2,2000; PCT Publication WO/00/57505, Barker, published Sep. 28, 2000; U.S.Pat. No. 6,136,472, Barker et al., issued Oct. 24, 2000; U.S. Pat. No.6,153,333, Barker, issued Nov. 28, 2000; European Patent Publication1,049,182, Ravet et al., published Nov. 2, 2000; PCT PublicationWO/01/13443, Barker, published Feb. 22, 2001; PCT PublicationWO/01/54212, Barker et al., published Jul. 26, 2001; PCT PublicationWO/01/84655, Barker et al., published Nov. 8, 2001.

Preferably, such a cathode material exhibits a high free energy ofreaction with lithium, is able to release and insert a large quantity oflithium, maintains its lattice structure upon insertion and extractionof lithium, allows rapid diffusion of lithium, affords good electricalconductivity, is not significantly soluble in the electrolyte system ofthe battery, and is readily and economically produced. However, many ofthe cathode materials known in the art lack one or more of thesecharacteristics. As a result, for example, many such materials are noteconomical to produce, afford insufficient voltage, have insufficientcharge capacity, or lose their ability to be recharged over multiplecycles.

SUMMARY OF THE INVENTION

The invention provides batteries comprising active materials comprisinglithium or other alkali metals, transition metals and optionally othermetals, and a phosphate, substituted phosphate or similar moiety. Inparticular, the present invention provides a lithium battery comprising

-   -   (A) a first electrode comprising an active material of the        formula        A_(a)M_(b)(XY₄)_(c)Z_(d),        wherein    -   (i.) A is selected from the group consisting of Li, Na, K, and        mixtures thereof, and 0<a≦9;    -   (ii.) M is one or more metals, comprising at least one metal        which is capable of undergoing oxidation to a higher valence        state, and 1≦b≦3;    -   (iii.) XY₄ is selected from the group consisting of        X′O_(4-x)Y+_(x), X′O_(4-y)Y′_(2y), X″S₄, and mixtures thereof,        where X′ is selected from the group consisting of P, As, Sb, Si,        Ge, V, S, and mixtures thereof; X″ is selected from the group        consisting of P, As, Sb, Si, Ge, V and mixtures thereof; Y′ is        selected from the group consisting of halogen, S, N, and        mixtures thereof; 0≦x<3; and 0<y≦2; and 0<c≦3;    -   (iv.) Z is OH, halogen, or mixtures thereof, and 0<d≦6; and    -   (v.) wherein M, XY₄, Z, a, b, c, d, x and y are selected so as        to maintain electroneutrality of said compound;    -   (B) a second electrode which is a counter-electrode to said        first electrode; and    -   (C) an electrolyte comprising a mixture of a cyclic ester and a        carbonate selected from the group consisting of alkyl        carbonates, alkylene carbonates, and mixtures thereof.

In a preferred embodiment, M comprises two or more transition metalsfrom Groups 4 to 11 of the Periodic Table. In another preferredembodiment, M comprises M′M″, where M′ is at least one transition metalfrom Groups 4 to 11 of the Periodic Table; and M″ is at least oneelement from Groups 2, 3, and 12-16 of the Periodic Table. Preferredembodiments include those where c=1, those where c=2, and those wherec=3. Preferred embodiments include those where a≦1 and c=1, those wherea=2 and c=1, and those where a≧3 and c=3. Preferred embodiments alsoinclude those having a structure similar to the mineral olivine (herein“olivines”), and those having a structure similar to NASICON (NA SuperIonic CONductor) materials (herein “NASICONs”). In a particularlypreferred embodiment, M comprises Co_(e)Fe_(f)M¹ _(g)M² _(h)M³ _(i),where M¹ is at least one transition metal from Groups 4 to 11 of thePeriodic Table; M² comprises one or more +2 oxidation statenon-transition metals, and M³ comprises one or more +3 oxidation statenon-transition metals, and e+f+g=b. In such an embodiment, preferably Acomprises Li, 0.8≦a≦1.2, 0.8≦b≦1.5, and c=1. As used herein, unlessotherwise specified, a variable described algebraically as equal to(“=”), less than or equal to (“≦”), or greater than or equal to (“≧”) anumber is intended to subsume values or ranges of values about equal orfunctionally equivalent to said number.

It has been found that the novel batteries of this invention affordbenefits over such materials and devices among those known in the art.Such benefits include one or more of increased capacity, enhancedcycling capability, enhanced reversibility, and reduced costs. Specificbenefits and embodiments of the present invention are apparent from thedetailed description set forth herein. It should be understood, however,that the detailed description and specific examples, while indicatingembodiments among those preferred, are intended for purposes ofillustration only and are not intended to limited the scope of theinvention.

DESCRIPTION OF THE INVENTION

The present invention provides batteries comprising certain electrodeactive materials and electrolytes. As used herein, “battery” refers to adevice comprising one or more electrochemical cells for the productionof electricity. Each electrochemical cell comprises an anode, a cathode,and an electrolyte. Two or more electrochemical cells may be combined,or “stacked,” so as to create a multi-cell battery having a voltage thatis the sum of the voltages of the individual cells.

The electrode active materials of this invention may be used in theanode, the cathode, or both. Preferably, the active materials of thisinvention are used in the cathode. (As used herein, the terms “anode”and “cathode” refer to the electrodes at which oxidation and reductionoccur, respectively, during battery discharge. During charging of thebattery, the sites of oxidation and reduction are reversed. Also, asused herein, the words “preferred” and “preferably” refer to embodimentsof the invention that afford certain benefits, under certaincircumstances. However, other embodiments may also be preferred, underthe same or other circumstances. Furthermore, the recitation of one ormore preferred embodiments does not imply that other embodiments are notuseful and is not intended to exclude other embodiments from the scopeof the invention.)

Electrode Active Materials:

The present invention provides active materials (herein “electrodeactive materials”) comprising lithium or other alkali metals, atransition metal, a phosphate or similar moiety, and (optionally) ahalogen or hydroxyl moiety. Such electrode active materials includethose of the formula A_(a)M_(b)(XY₄)_(c)Z_(d). (As used herein, the word“include,” and its variants, is intended to be non-limiting, such thatrecitation of items in a list is not to the exclusion of other likeitems that may also be useful in the materials, compositions, devices,and methods of this invention.)

A is selected from the group consisting of Li (lithium), Na (sodium), K(potassium), and mixtures thereof. In a preferred embodiment, A is Li, amixture of Li with Na, a mixture of Li with K, or a mixture of Li, Naand K. In another preferred embodiment, A is Na, or a mixture of Na withK. Preferably “a” is from about 0.1 to about 6, more preferably fromabout 0.2 to about 6. Where c=1, a is preferably from about 0.1 to about3, preferably from about 0.2 to about 2. In a preferred embodiment,where c=1, a is less than about 1. In another preferred embodiment,where c=1, a is about 2. Preferably “a” is from about 0.8 to about 1.2.Where c=2, a is preferably from about 0.1 to about 6, preferably fromabout 1 to about 6. Where c=3, a is preferably from about 0.1 to about6, preferably from about 2 to about 6, preferably from about 3 to about6. In another embodiment, “a” is preferably from about 0.2 to about 1.0.

In a preferred embodiment, removal of alkali metal from the electrodeactive material is accompanied by a change in oxidation state of atleast one of the metals comprising M. The amount of said metal that isavailable for oxidation in the electrode active material determines theamount of alkali metal that may be removed. Such concepts are, ingeneral application, well known in the art, e.g., as disclosed in U.S.Pat. No. 4,477,541, Fraioli, issued Oct. 16, 1984; and U.S. Pat. No.6,136,472, Barker, et al., issued Oct. 24, 2000, both of which areincorporated by reference herein.

Referring to the general formula A_(a)M_(b)(XY₄)_(c)Z_(d), the amount(a′) of alkali metal that can be removed, as a function of the quantityof (b′) and valence state (V^(M)) of oxidizable metal (M), isa′=b′(ΔV^(M)),where ΔV^(M) is the difference between the valence state of the metal inthe active material and a valence state readily available for the metal.(The term oxidation state and valence state are used in the artinterchangeably.) For example, for an active material comprising iron(Fe) in the +2 oxidation state, ΔV^(M)=1, wherein iron may be oxidizedto the +3 oxidation state (although iron may also be oxidized to a +4oxidation state in some circumstances). If b=1 (one atomic unit of Feper atomic unit of material), the maximum amount (a′) of alkali metal(oxidation state +1) that can be removed during cycling of the batteryis 1 (one atomic units of alkali metal). If b=1.25, the maximum amountof (a′) of alkali metal that can be removed during cycling of thebattery is 1.25.

In general, the value of “a” in the active materials can vary over awide range. In a preferred embodiment, active materials are synthesizedfor use in preparing a lithium ion battery in a discharged state. Suchactive materials are characterized by a relatively high value of “a”,with a correspondingly low oxidation state of M of the active material.As the battery is charged from its initial uncharged state, an amount a′of lithium is removed from the active material as described above. Theresulting structure, containing less lithium (i.e., a-a′) than in theas-prepared state as well as the transition metal in a higher oxidationstate than in the as-prepared state, is characterized by lower values ofa, while essentially maintaining the original value of b. The activematerials of this invention include such materials in their nascentstate (i.e., as manufactured prior to inclusion in an electrode) andmaterials formed during operation of the battery (i.e., by insertion orremoval of Li or other alkaline metal).

The value of “b” and the total valence of M in the active material mustbe such that the resulting active material is electrically neutral(i.e., the positive charges of all cationic species in the materialbalance the negative charges of all anionic species), as furtherdiscussed below. The net valence of M (V^(M)) having a mixture ofelements (M1, M2 . . . Mt) may be represented by the formulaV^(M)=V^(M1) b ₁+V^(M2) b ₂+ . . . V^(Mt) b _(t),where b₁+b₂+ . . . b_(t)=1, and V^(M1) is the oxidation state of M1,V^(M2) is the oxidation state of M2, etc.. (The net valence of M andother components of the electrode active material is discussed further,below.)

M is one or more metals including at least one metal that is capable ofundergoing oxidation to a higher valence state (e.g., Co⁺²→Co⁺³),preferably a transition metal selected from Groups 4-11 of the PeriodicTable. As referred to herein, “Group” refers to the Group numbers (i.e.,columns) of the Periodic Table as defined in the current IUPAC PeriodicTable. See, e.g., U.S. Pat. No. 6,136,472, Barker et al., issued Oct.24, 2000, incorporated by reference herein. In another preferredembodiment, M further comprises a non-transition metal selected fromGroups 2, 3, and 12-16 of the Periodic Table.

In another preferred embodiment, preferably where c=1, M comprisesCo_(e),Fe_(f)M¹ _(g)M² _(h)M³ _(i), wherein M¹ is at least onetransition metal from Groups 4 to 11, M² is at least one +2 oxidationstate non-transition metal, M³ is at least one +3 oxidation state nontransition metal, e≧0, f≧0, g≧0, h≧0, i≧0 and (e+f+g+h+i)=b. Preferably,at least one of e and f are greater than zero, more preferably both. Ina preferred embodiment 0<(e+f+g+h+i)≦2, more preferably 0.8≦(e+f+g)≦1.2,and even more preferably 0.9≦(e+f+g)≦1.0. Preferably, e≧0.5, morepreferably e≧0.8. Preferably, 0.01≦f≦0.5, more preferably 0.05≦f≦0.15.Preferably, 0.01≦g≦0.5, more preferably 0.05≦g≦0.2. In a preferredembodiment, (h+i)>1, preferably 0.01≦(h+i)≦0.5, and even more preferably0.01≦(h+i)≦0.1. Preferably, 0.01≦h≦0.2, more preferably 0.01≦h≦0.1.Preferably 0.01≦i≦0.2, more preferably 0.01≦i≦0.1.

Transition metals useful herein include those selected from the groupconsisting of Ti (Titanium), V (Vanadium), Cr (Chromium), Mn(Manganese), Fe (Iron), Co (Cobalt), Ni (Nickel), Cu (Copper), Zr(Zirconium), Nb (Niobium), Mo (Molybdenum), Ru (Ruthenium), Rh(Rhodium), Pd (Palladium), Ag (Silver), Cd (Cadmium), Hf (Hafnium), Ta(Tantalum), W (Tungsten), Re (Rhenium), Os (Osmium), Ir (Iridium), Pt(Platinum), Au (Gold), Hg (Mercury), and mixtures thereof. Preferred arethe first row transition series (the 4th Period of the Periodic Table),selected from the group consisting of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, andmixtures thereof. Particularly preferred transition metals include thoseselected from the group consisting of Fe, Co, Ti, Mn, and mixturesthereof. In a preferred embodiment, M is Co_(1-m)Fe_(m), where 0<m≦0.5.Preferably 0.01<m≦0.2. Although, a variety of oxidation states for suchtransition metals are available, in some embodiments it is mostpreferable that the transition metals have a +2 oxidation state. As usedherein, the recitation of a genus of elements, materials or othercomponents, from which an individual component or mixture of componentscan be selected, is intended to include all possible sub-genericcombinations of the listed components, and mixtures thereof.

In a preferred embodiment, M further comprises one or morenon-transition metals. As referred to herein, “non-transition metals”include metals and metalloids from Groups 2, 3, and 12-16 of thePeriodic Table that are capable of forming stable active materials anddo not significantly impede the insertion or removal of lithium or otheralkaline metals from the active materials under normal operatingconditions. Preferably, such elements do not include C (carbon), Si(silicon), N (nitrogen) and P (phosphorus). Preferred non-transitionmetals include those not readily capable of undergoing oxidation to ahigher valence state in the electrode active material under normaloperating conditions. Among the non-transition metals useful herein arethose selected from the group consisting of Group 2 elements,particularly Be (Beryllium), Mg (Magnesium), Ca (Calcium), Sr(Strontium), Ba (Barium); Group 3 elements, particularly Sc (Scandium),Y (Yttrium), and the lanthanides, particularly La (Lanthanum), Ce(Cerium), Pr (Praseodymium), Nd (Neodymium), Sm (Samarium); Group 12elements, particularly Zn (zinc) and Cd (cadmium); Group 13 elements,particularly B (Boron), Al (Aluminum), Ga (Gallium), In (Indium), Tl(Thallium); Group 14 elements, particularly Si (Silicon), Ge(Germanium), Sn (Tin), and Pb (Lead); Group 15 elements, particularly As(Arsenic), Sb (Antimony), and Bi (Bismuth); Group 16 elements,particularly Te (Tellurium); and mixtures thereof. Preferrednon-transition metals include the Group 2 elements, Group 12 elements,Group 13 elements, and Group 14 elements. Particularly preferrednon-transition metals include those selected from the group consistingof Mg, Ca, Zn, Sr, Pb, Cd, Sn, Ba, Be, Al, and mixtures thereof.Particularly preferred are non-transition metals selected from the groupconsisting of Mg, Ca, Zn, Ba, Al, and mixtures thereof.

As further discussed herein, “b” is selected so as to maintainelectroneutrality of the electrode active material. In a preferredembodiment, where c=1, b is from about 1 to about 2, preferably about 1.In another preferred embodiment, where c=2, b is from about 2 to about3, preferably about 2.

XY₄ is an anion, preferably selected from the group consisting ofX′O_(4-x)Y′_(x), X′O_(4-y)Y′_(2y), X″S₄, and mixtures thereof, where X′is selected from the group consisting of P (phosphorus), As (arsenic),Sb (antimony), Si (silicon), Ge (germanium), V (vanadium) S (sulfur),and mixtures thereof; X″ is selected from the group consisting of P, As,Sb, Si, Ge, V, and mixtures thereof. XY₄ anions useful herein includephosphate, silicate, germanate, vanadate, arsenate, antimonate, sulfuranalogs thereof, and mixtures thereof. In a preferred embodiment, X′ andX″ are each selected from the group consisting of P, Si, and mixturesthereof. In a particularly preferred embodiment, X′ and X″ are P.

Y′ is selected from the group consisting of halogen, S, N, and mixturesthereof. Preferably Y′ is F (fluorine).ln a preferred embodiment 0≦x≦3;and 0<y≦2, such that a portion of the oxygen (O) in the XY₄ moiety issubstituted with halogen. In another preferred embodiment, x and y are0. In a particularly preferred embodiment XY₄ is X′O₄, where X′ ispreferably P or Si, more preferably P. In another particularly preferredembodiment, XY₄ is PO_(4-x)Y′_(x), where Y′ is halogen and 0<x≦1.Preferably 0.01≦x≦0.05, more preferably 0.02≦x≦0.03.

In a preferred embodiment, XY₄ is PO₄ (a phosphate group) or a mixtureof PO₄ with another XY₄ group (i.e., where X′ is not P, Y′ is not O, orboth, as defined above). When part of the phosphate group issubstituted, it is preferred that the substitute group be present in aminor amount relative to the phosphate. In a preferred embodiment, XY₄comprises 80% or more phosphate and up to about 20% of one or morephosphate substitutes. Phosphate substitutes include, withoutlimitation, silicate, sulfate, antimonate, germanate, arsenate,monofluoromonophosphate, difluoromonophosphate, sulfur analogs thereof,and combinations thereof. Preferably, XY₄ comprises a maximum of about10% of a phosphate substitute or substitutes. (The percentages are basedon mole percent.) Preferred XY₄ groups include those of the formula(PO₄)_(1-k)(B)_(k), where B represents an XY₄ group or combination ofXY₄ groups other than phosphate, and k≦0.5. Preferably, k≦0.8, morepreferably less than about k≦0.2, more preferably k≦0.1.

Z is OH, halogen, or mixtures thereof. In a preferred embodiment, Z isselected from the group consisting of OH (hydroxyl), F (fluorine), Cl(chlorine), Br (bromine) and mixtures thereof. In a preferredembodiment, Z is OH. In another preferred embodiment, Z is F, ormixtures of F with OH, Cl, or Br. In one preferred embodiment, d=0. Inanother preferred embodiment, d>0, preferably from about 0.1 to about 6,more preferably from about 0.2 to about 6. In such embodiments, wherec=1, d is preferably from about 0.1 to about 3, preferably from about0.2 to about 2. In a preferred embodiment, where c=1, d is about 1.Where c=2, d is preferably from about 0.1 to about 6, preferably fromabout 1 to about 6. Where c=3, d is preferably from about 0.1 to about6, preferably from about 2 to about 6, preferably from about 3 to about6.

The composition of M, XY₄, Z and the values of a, b, c, d, x, and y areselected so as to maintain electroneutrality of the electrode activematerial. As referred to herein “electroneutrality” is the state of theelectrode active material wherein the sum of the positively chargedspecies (e.g., A and M) in the material is equal to the sum of thenegatively charged species (e.g., XY₄) in the material. Preferably, theXY₄ moieties are comprised to be, as a unit moiety, an anion having acharge of −2, −3, or −4, depending on the selection of X′, X″, Y′, and xand y. When XY₄ is a mixture of groups such as the preferredphosphate/phosphate substitutes discussed above, the net charge on theXY₄ anion may take on non-integer values, depending on the charge andcomposition of the individual groups XY₄ in the mixture.

In general, the valence state of each component element of the electrodeactive material may be determined in reference to the composition andvalence state of the other component elements of the material. Byreference to the general formula A_(a)M_(b)(XY₄)_(c)Z_(d), theelectroneutrality of the material may be determined using the formula(V^(A))a+(V^(M))b+(V^(X))c=(V^(Y))4c+(V^(Z))dwhere V^(A) is the net valence of A, V^(M) is the net valence of M,V^(Y) is the net valence of Y, and V^(Z) is the net valence of Z. Asreferred to herein, the “net valence” of a component is (a) the valencestate for a component having a single element which occurs in the activematerial in a single valence state; or (b) the mole-weighted sum of thevalence states of all elements in a component comprising more than oneelement, or comprising a single element having more than one valencestate. The net valence of each component is represented in the followingformulae.(V^(A))b=[(V^(A1))a ¹+(Val^(A2))a ²+ . . . (V^(An))a ^(n) ]/n; a ¹ +a² + . . . a ^(n) =a(V^(M))b=[(V^(M1))b ¹+(V^(M2))b ²+ . . . (V^(Mn))b ^(n) ]/n; b ¹ +b ² +. . . b ^(n) =b(V^(X))c=[(V^(X1))c ¹+(V^(X2))c ²+ . . . (V^(Xn))c ^(n) ]/n; c ¹ +c ²+ .. . c^(n) =c(V^(Y))c=[(V^(Y1))c ¹+(V^(Y2))c ²+ . . . (V^(Yn))c ^(n) ]/n; c ¹ +c ² +. . . c ^(n) =c(V^(Z))d=[(V^(Z1))d ¹+(V^(Z2))d ²+ . . . (V^(Zn))d ^(n) ]/n; d ¹ +d ² +. . . d ^(n) =d

In general, the quantity and composition of M is selected given thevalency of X, the value of “c,” and the amount of A, so long as Mcomprises at least one metal that is capable of oxidation. Thecalculation for the valence of M can be simplified, where V^(A)=1,V^(Z)=1, as follows.For compounds where c=1: (V^(M))b=(V^(Y))4+d−a−(V^(X))For compounds where c=3: (V^(M))b=(V^(Y))12+d−a−(V^(X))3

The values of a, b, c, d, x, and y may result in stoichiometric ornon-stoichiometric formulas for the electrode active materials. In apreferred embodiment, the values of a, b, c, d, x, and y are all integervalues, resulting in a stoichiometric formula. In another preferredembodiment, one or more of a, b, c, d, x and y may have non-integervalues. It is understood, however, in embodiments having a latticestructure comprising multiple units of a non-stoichiometric formulaA_(a)M_(b)(XY₄)_(c)Z_(d), that the formula may be stoichiometric whenlooking at a multiple of the unit. That is, for a unit formula where oneor more of a, b, c, d, x, or y is a non-integer, the values of eachvariable become an integer value with respect to a number of units thatis the least common multiplier of each of a, b, c, d, x and y. Forexample, the active material Li₂Fe_(0.5)Mg_(0.5)PO₄F isnon-stoichiometric. However, in a material comprising two of such unitsin a lattice structure, the formula is Li₄FeMg(PO₄)₂F₂.

A preferred electrode active material embodiment comprises a compound ofthe formulaLi_(a)M_(b)(PO₄)Z_(d),wherein

-   -   (1) 0.1<a≦4;    -   (2) M is M′_(1-m)M″_(m), where M′ is at least one transition        metal from Groups 4 to 11 of the Periodic Table; M″ is at least        one non-transition metal from Groups 2, 3, and 12-16 of the        Periodic Table, 0<m<1, and 1≦b≦3; and    -   (3) Z comprises halogen, and 0≦d≦4; and

wherein M, Z, a, b, and d are selected so as to maintainelectroneutrality of said compound. Preferably, M′ is selected from thegroup consisting of Fe, Co, Ni, Mn, Cu, V, Zr, Ti, Cr, and mixturesthereof; more preferably M′ is selected from the group consisting of Fe,Co, Mn, Cu, V, Cr, and mixtures thereof. Preferably, M″ is selected fromthe group consisting of Mg, Ca, Zn, Sr, Pb, Cd, Sn, Ba, Be, Al, andmixtures thereof; more preferably M″ is selected from the groupconsisting of Mg, Ca, Zn, Ba, Al, and mixtures thereof. Preferably Zcomprises F.

Another preferred embodiment comprises a compound of the formula:A_(a)M_(b)(XY₄)₃Z_(d),wherein

-   -   (1) A is selected from the group consisting of Li, Na, K, and        mixtures thereof, and 2>a>9;    -   (2) M comprises one or more metals, comprising at least one        metal which is capable of undergoing oxidation to a higher        valence state, and 1≦b≦3;    -   (3) XY₄ is selected from the group consisting of        X′O_(4-x)Y+_(x), X′O_(4-y)Y′_(2y), X″S₄, and mixtures thereof,        where X′ is selected from the group consisting of P, As, Sb, Si,        Ge, V, S, and mixtures thereof; X″ is selected from the group        consisting of P, As, Sb, Si, Ge, V, and mixtures thereof; Y′ is        selected from the group consisting of halogen, S, N, and        mixtures thereof; 0≦x<3; and 0<y<4; and    -   (4) Z is OH, halogen, or mixtures thereof, and 0>d>6; and    -   (5) wherein M, XY₄, Z, a, b, d, x and y are selected so as to        maintain electroneutrality of said compound.

In a preferred embodiment, A comprises Li, or mixtures of Li with Na orK. In another preferred embodiment, A comprises Na, K, or mixturesthereof. In a preferred embodiment, M comprises two or more transitionmetals from Groups 4 to 11 of the Periodic Table, preferably transitionmetals selected from the group consisting of Fe, Co, Ni, Mn, Cu, V, Zr,Ti, Cr, and mixtures thereof. In another preferred embodiment, Mcomprises M′_(1-m)M″_(m), where M′ is at least one transition metal fromGroups 4 to 11 of the Periodic Table; and M″ is at least one elementfrom Groups 2, 3, and 12-16 of the Periodic Table; and 0<m<1.Preferably, M′ is selected from the group consisting of Fe, Co, Ni, Mn,Cu, V, Zr, Ti, Cr, and mixtures thereof; more preferably M′ is selectedfrom the group consisting of Fe, Co, Mn, Cu, V, Cr, and mixturesthereof. Preferably, M″ is selected from the group consisting of Mg, Ca,Zn, Sr, Pb, Cd, Sn, Ba, Be, Al, and mixtures thereof; more preferably,M″ is selected from the group consisting of Mg, Ca, Zn, Ba, Al, andmixtures thereof. In a preferred embodiment, XY₄ is PO₄. In anotherpreferred embodiment, X′ comprises As, Sb, Si, Ge, S, and mixturesthereof; X″ comprises As, Sb, Si, Ge and mixtures thereof; and 0<x<3. Ina preferred embodiment, Z comprises F, or mixtures of F with Cl, Br, OH,or mixtures thereof. In another preferred embodiment, Z comprises OH, ormixtures thereof with Cl or Br.

Another preferred embodiment comprises a compound of the formulaA_(a)M¹ _(e)M² _(f)M³ _(g)XY₄,wherein

-   -   (1) A is selected from the group consisting of Li, Na, K, and        mixtures thereof, and 0<a≦2;    -   (2) M¹ comprises one or more transition metals, where e>0;    -   (3) M² comprises one or more +2 oxidation state non transition        metals, where f>0;    -   (4) M³ comprises one or more +3 oxidation state non-transition        metal, where g>0; and    -   (5) XY₄ is selected from the group consisting of        X+O_(4-x)Y′_(x), X′O_(4-y)Y′_(2y), X″S₄, and mixtures thereof,        where X′ is selected from the group consisting of P, As, Sb, Si,        Ge, V, S, and mixtures thereof; X″ is selected from the group        consisting of P, As, Sb, Si, Ge, V, and mixtures thereof; Y′ is        selected from the group consisting of halogen, S, N, and        mixtures thereof; 0≦x≦3; and 0<y≦2; and    -   (6) wherein e+f+g<2, and M¹, M², M³, XY₄, a, e, f, g, x, and y        are selected so as to maintain electroneutrality of said        compound.

In embodiments where XY₄ is PO_(4-x)Y+_(x) and M¹ is a +2 oxidationstate transition metal, a+2e+2f+3g=3−x.

Preferably, e+f+g=b. In a preferred embodiment 0<(e+f+g)<2, morepreferably 0.8≦(e+f+g)≦1.5, and even more preferably 0.9≦(e+f+g)≦1,wherein 0.01≦(f+g)≦0.5, more preferably 0.05≦(f+g)≦0.2, and even morepreferably 0.05≦(f+g)≦0.1.

In a preferred embodiment, A is Li. Preferably, M¹ is at least onetransition metal from Groups 4 to 11 of the Periodic Table; M² is atleast one non-transition metal from Groups 2, 3, and 12-16 of thePeriodic Table, and M³ is a +3 oxidation state metal selected from Group13. Preferably M¹ is selected from the group consisting of Fe, Co, Ni,Mn, Cu, V, Zr, Ti, Cr, and mixtures thereof; more preferably M¹ is a +2oxidation state transition metal selected from the group consisting ofFe, Co, Mn, Cu, V, Cr, and mixtures thereof. Preferably M² is selectedfrom the group consisting +2 oxidation state non-transition metals andmixtures thereof; more preferably M² is selected from the groupconsisting of Be, Mg, Ca, Sr, Ba, Ra, Zn, Cd, Hg and mixtures thereof.Preferably, M³ is a +3 oxidation state non-transition metal, preferablyM³ is selected from Group 13, more preferably Sc, Y, La, Ac, B, Al, Ga,In, Tl and mixtures thereof. Preferably M³ is Al. Preferably 0<(f+g)<1,preferably 0.01≦(f+g)≦0.3, more preferably 0.05≦(f+g)≦0.1. Preferably,0.01≦f≦0.3, more preferably 0.05≦f≦0.1, and even more preferably0.01≦f≦0.03. Also preferably, 0.01≦g≦0.3, more preferably 0.05≦g≦0.1,and even more preferably 0.01≦g≦0.03.

Another preferred embodiment comprises a compound of the formulaLi_(a)Co_(e)Fe_(f)M¹ _(g)M² _(h)M³ _(i)XY₄wherein

-   -   (1) 0<a≦2,e>0,and f>0;    -   (2) M¹ is one or more transition metals, where g≧0;    -   (3) M² is one or more +2 oxidation state non-transition metals,        where h≧0;    -   (4) M³ is one or more +3 oxidation state non-transition metals,        where i≧0; and    -   (5) XY₄ is selected from the group consisting of        X′O_(4-x)Y′_(x), X′O_(4-y)Y′_(2y), X″S₄, and mixtures thereof,        where X′ is selected from the group consisting of P, As, Sb, Si,        Ge, V, S, and mixtures thereof; X″ is selected from the group        consisting of P, As, Sb, Si, Ge, V, and mixtures thereof; Y′ is        selected from the group consisting of halogen, S, N, and        mixtures thereof; 0≦x≦3; and 0<y≦2;    -   (1) wherein (e+f+g+h+i)≦2, and M¹, M², M³, XY₄, a, e, f, g, h,        i, x, and y are selected so as to maintain electroneutrality of        said compound.

Preferably, 0.8≦(e+f+g+h+i)≦1.2, more preferably 0.95≦(e+f+g+i)≦1.Preferably, e≧0.5, more preferably, e≧0.8. Preferably, 0.01≦f≦0.5, morepreferably, 0.05≦f≦0.15. Preferably, 0.01≦g≦0.5, more preferably,0.05≦g≦0.2. Preferably M¹ is selected from the group consisting of Ti,V, Cr, Mn, Ni, Cu and mixtures thereof. Preferably, M¹ is selected fromthe group consisting of Mn, Ti, and mixtures thereof.

Preferably, (h+i)>0, more preferably 0.01≦(h+i)≦0.5, more preferably0.02≦(h+i)≦0.3. Preferably, 0.01≦h≦0.2, more preferably, 0.01≦h≦0.1.Preferably, M² is selected from the group consisting of Be, Mg, Ca, Sr,Ba, and mixtures thereof. More preferably, M² is Mg. Preferably,0.01≦i≦0.2, more preferably 0.01≦i≦0.1. Preferably, M³ is selected fromthe group consisting of B, Al, Ga, In, and mixtures thereof. Morepreferably, M³ is Al.

In one embodiment, XY₄ is PO₄. In another embodiment, XY₄ isPO_(4-x)F_(x), and 0<x≦1, preferably, 0.01≦x≦0.05.

Another preferred embodiment comprises a compound having an olivinestructure. During charge and discharge of the battery, lithium ions areadded to, and removed from, the active material preferably withoutsubstantial changes in the crystal structure of the material. Suchmaterials have sites for the alkali metal (e.g., Li), the transitionmetal (M), and the XY₄ (e.g., phosphate) moiety. In some embodiments,all sites of the crystal structure are occupied. In other embodiments,some sites may be unoccupied, depending on, for example, the oxidationstates of the metal (M). Among such preferred compounds are those of theformulaLiM(PO_(4-x)Y′_(x))wherein M is M¹ _(g)M² _(h)M³ _(i)M⁴ _(j), and

-   -   (1) M¹ is one or more transition metals;    -   (2) M² is one or more +2 oxidation state non-transition metals;    -   (3) M³ is one or more +3 oxidation state non-transition metals,    -   (4) M⁴ is one or more +1 oxidation state non-transition metals;        and    -   (5) Y′ is halogen; and    -   (6) g,>0; h≧0; i≧0; j≧0; (g+h+i+j)≦1; and the net valence of M        is 2-x.

Preferably, g≧0.8, more preferably, g≧0.9. Preferably, M¹ is a +2oxidation state transition metal selected from the group consisting ofV, Cr, Mn, Fe, Co, Ni, and mixtures thereof. More preferably, M¹ isselected from the group consisting of Fe, Co, and mixtures thereof.Preferably M¹ additionally comprises Ti.

Preferably, (h+i)>0.1, more preferably, 0.02≦(h+i)≦0.5, more preferably,0.02≦(h+i)≦0.3. Preferably, 0.01≦h≦0.2, more preferably, 0.01≦h≦0.1.Preferably, M² is selected from the group consisting of Be, Mg, Ca, Sr,Ba, and mixtures thereof. Preferably, 0.01≦i≦0.2, more preferably,0.01≦i≦0.1. Preferably, M³ is Al.

In one embodiment, j=0. In another embodiment, 0.01≦j≦0.1. Preferably,M⁴ is selected from the group consisting of Li, Na, and K. Morepreferably, M⁴ is Li.

In one embodiment, x=0. In another embodiment, 0<x≦1. In such anembodiment, preferably, 0.01≦x≦0.05, and (g+h+i+j)<1. In an embodimentwhere j=0, preferably, (g+h+i)=1−x.

Non-limiting examples of active materials of the invention include thefollowing: Li_(0.95)Co_(0.8)Fe_(0.15)Al_(0.05)PO₄,Li_(1.025)Co_(0.85)Fe_(0.05)Al_(0.025)Mg_(0.05)PO₄,Li_(1.025)Co_(0.80)Fe_(0.10)Al_(0.025)Mg_(0.05)PO₄,Li_(1.025)Co_(0.45)Fe_(0.45)Al_(0.025)Mg_(0.05)PO₄,Li_(1.025)Co_(0.75)Fe_(0.15)Al_(0.025)Mg_(0.05)PO₄,Li_(1.025)Co_(0.7)(Fe_(0.4)Mn_(0.6))_(0.2)Al_(0.025)Mg_(0.05)PO₄,Li_(1.025)CO_(0.75)Fe_(0.15)Al_(0.025)Mg_(0.05)PO₄,Li_(1.025)Co_(0.85)Fe_(0.05)Al_(0.025)Mg_(0.05)PO₄,Li_(1.025)Co_(0.7)Fe_(0.08)Mn_(0.12)Al_(0.025)Mg_(0.05)PO₄,LiCo_(0.75)Fe_(0.15)Al_(0.025)Ca_(0.05)PO_(3.975)F_(0.025),LiCo_(0.80)Fe_(0.10)Al_(0.025)Ca_(0.05)PO_(3.975)F_(0.025),Li_(1.25)Co_(0.6)Fe_(0.1)Mn_(0.075)Mg_(0.025)Al_(0.05)PO₄,Li_(0.1)Na_(0.25)Co_(0.6)Fe_(0.1)Cu_(0.075)Mg_(0.025)Al_(0.05)PO₄,Li_(1.025)Co_(0.8)Fe_(0.1)Al_(0.025)Mg_(0.075)PO₄,Li_(1.025)Co_(0.6)Fe_(0.05)Al_(0.12)Mg_(0.0325)PO_(3.75)F_(0.25),Li_(1.025)Co_(0.7)Fe_(0.1)Mg_(0.025)Al_(0.04)PO_(3.75)F_(0.25),Li_(0.75)Co_(0.5)Fe_(0.05)Mg_(0.015)Al_(0.04)PO₃F,Li_(0.75)Co_(0.5)Fe_(0.025)Cu_(0.025)Be_(0.015)Al_(0.04)PO₃F,Li_(0.75)Co_(0.5)Fe_(0.025)Mn_(0.025)Ca_(0.015)Al_(0.04)PO₃F,Li_(1.025)Co_(0.6)Fe_(0.05)B_(0.12)Ca_(0.0325)PO_(3.75)F_(0.25),Li_(1.025)Co_(0.65)Fe_(0.05)Mg_(0.0125)Al_(0.1)PO_(3.75)F_(0.25),Li_(1.025)Co_(0.65)Fe_(0.05)Mg_(0.065)Al_(0.14)PO_(3.975)F_(0.025),Li_(1.075)Co_(0.8)Fe_(0.05)Mg_(0.025)Al_(0.05)PO_(3.975)F_(0.025);LiCo_(0.8)Fe_(0.1)Al_(0.025)Mg_(0.05)PO_(3.975)F_(0.025),Li_(0.25)Fe_(0.7)Al_(0.45)PO₄, LiMnAl_(0.067)(PO₄)_(0.8)(SiO₄)_(0.2),Li_(0.95)Co_(0.9)Al_(0.05)Mg_(0.05)PO₄,Li_(0.95)Fe_(0.8)Ca_(0.15)Al_(0.05)PO₄,Li_(0.25)MnBe_(0.425)Ga_(0.3)SiO₄,Li_(0.5)Na_(0.25)Mn_(0.6)Ca_(0.375)Al_(0.1)PO₄,Li_(0.25)Al_(0.25)Mg_(0.25)Co_(0.75)PO₄,Na_(0.55)B_(0.15)Ni_(0.75)Ba_(0.25)PO₄,Li_(1.025)Co_(0.9)Al_(0.025)Mg_(0.05)PO₄,K_(1.025)Ni_(0.99)Al_(0.025)Ca_(0.05)PO₄,Li_(0.95)Co_(0.9)Al_(0.05)Mg_(0.05)PO₄,Li_(0.95)Fe_(0.8)Ca_(0.15)Al_(0.05)PO₄,Li_(1.025)Co_(0.7)(Fe_(0.4)Mn_(0.6))_(0.2)Al_(0.025)Mg_(0.05)PO₄,Li_(1.025)Co_(0.8)Fe_(0.1)Al_(0.025)Mg_(0.05)PO₄,Li_(1.025)Co_(0.9)Al_(0.025)Mg_(0.05)PO₄,Li_(1.025)Co_(0.75)Fe_(0.15)Al_(0.025)Mg_(0.025)PO₄,LiCo_(0.75)Fe_(0.15)Al_(0.025)Ca_(0.05)PO_(3.975)F_(0.025),LiCo_(0.9)Al_(0.025)Mg_(0.05)PO_(3.975)F_(0.025),Li_(0.75)Co_(0.625)Al_(0.25)PO_(3.75)F_(0.25),Li_(1.075)Co_(0.8)Cu_(0.05)Mg_(0.025)Al_(0.05)PO_(3.975)F_(0.025),Li_(1.075)Fe_(0.8)Mn_(0.075)Al_(0.05)PO_(3.975)F_(0.025),Li_(1.075)Co_(0.8)Mg_(0.075)Al_(0.05)PO_(3.975)F_(0.025),Li_(1.025)Co_(0.8)Mg_(0.1)Al_(0.05)PO_(3.975)F_(0.025),LiCo_(0.7)Fe_(0.2)Al_(0.025)Mg_(0.05)PO_(3.975)F_(0.025),Li₂Fe_(0.8)Mg_(0.2)PO₄F; Li₂Fe_(0.5)Co_(0.5)PO₄F; Li₃CoPO₄F₂;KFe(PO₃F)F; Li₂Co(PO₃F)Br₂; Li₂Fe(PO₃F₂)F; Li₂FePO₄Cl; Li₂MnPO₄OH;Li₂CoPO₄F; Li₂Fe_(0.5)Co_(0.5)PO₄F; Li₂Fe_(0.9)Mg_(0.1)PO₄F;Li₂Fe_(0.8)Mg_(0.2)PO₄F; Li_(1.25)Fe_(0.9)Mg_(0.1)PO₄F_(0.25);Li₂MnPO₄F; Li₂CoPO₄F; K₂Fe_(0.9)Mg_(0.1)P_(0.5)As_(0.5)O₄F; Li₂MnSbO₄OH;Li₂Fe_(0.6)Co_(0.4)SbO₄Br; Na₃CoAsO₄F₂; LiFe(AsO₃F)Cl;Li₂Co(As_(0.5)Sb_(0.5)O₃F)F₂; K₂Fe(AsO₃F₂)F; Li₂NiSbO₄F; Li₂FeAsO₄OH;Li₄Mn₂(PO₄)₃F; Na₄FeMn(PO₄)₃OH; Li₄FeV(PO₄)₃Br; Li₃VAl(PO₄)₃F;K₃VAl(PO₄)₃Cl; LiKNaTiFe(PO₄)₃F; Li₄Ti₂(PO₄)₃Br; Li₃V₂(PO₄)₃F₂;Li₆FeMg(PO₄)₃OH; Li₄Mn₂(AsO₄)₃F; K₄FeMn(AsO₄)₃OH;Li₄FeV(P_(0.5)Sb_(0.5)O₄)₃Br; LiNaKAlV(AsO₄)₃F; K₃VAl(SbO₄)₃Cl;Li₃TiV(SbO₄)₃F; Li₂FeMn(P_(0.5)As_(0.5)O₃F)₃; Li₄Ti₂(PO₄)₃F;Li_(3.25)V₂(PO₄)₃F_(0.25); Li₃Na_(0.75)Fe₂(PO₄)₃F_(0.75);Na_(6.5)Fe₂(PO₄)₃(OH)Cl_(0.5); K₈Ti₂(PO₄)₃F₃Br₂; K₈Ti₂(PO₄)₃F₅;Li₄Ti₂(PO₄)₃F; LiNa_(1.25)V₂(PO₄)₃F_(0.5)Cl_(0.75);K_(3.25)Mn₂(PO₄)₃OH_(0.25); LiNa_(1.25)KTiV(PO₄)₃(OH)_(1.25)Cl;Na₈Ti₂(PO₄)₃F₃Cl₂; Li₇Fe₂(PO₄)₃F₂; Li₈FeMg(PO₄)₃F_(2.25)Cl_(0.75);Li₅Na_(2.5)TiMn(PO₄)₃(OH)₂Cl_(0.5); Na₃K_(4.5)MnCa(PO₄)₃(OH)_(1.5)Br;K₉FeBa(PO₄)₃F₂Cl₂; Li₇Ti₂(SiO₄)₂(PO₄)F₂; Na₈Mn₂(SiO₄)₂(PO₄)F₂Cl;Li₃K₂V₂(SiO₄)₂(PO₄)(OH)Cl; L₄Ti₂(SiO₄)₂(PO₄)(OH); Li₂NaKV₂(SiO₄)₂(PO₄)F;Li₅TiFe(PO₄)₃F; Na₄K₂VMg(PO₄)₃FCl; Li₄NaAlNi(PO₄)₃(OH);Li₄K₃FeMg(PO₄)₃F₂; Li₂Na₂K₂CrMn(PO₄)₃(OH)Br; Li₅TiCa(PO₄)₃F;Li₄Ti_(0.75)Fe_(1.5)(PO₄)₃F; Li₃NaSnFe(PO₄)₃(OH);Li₃NaGe_(0.5)Ni₂(PO₄)₃(OH); Na₃K₂VCo(PO₄)₃(OH)Cl; Li₄Na₂MnCa(PO₄)₃F(OH);Li₃NaKTiFe(PO₄)₃F; Li₇FeCo(SiO₄)₂(PO₄)F; Li₃Na₃TiV(SiO₄)₂(PO₄)F;K_(5.5)CrMn(SiO₄)₂(PO₄)Cl_(0.5); Li₃Na_(2.5)V₂(SiO₄)₂(PO₄)(OH)_(0.5);Na_(5.25)FeMn(SiO₄)₂(PO₄)Br_(0.25); Li_(6.5)VCo(SiO₄)_(2.5)(PO₄)_(0.5)F;Na_(7.25)V₂(SiO₄)_(2.25)(PO₄)_(0.75)F₂; Li₄NaVTi(SiO₄)₃F_(0.5)Cl_(0.5);Na₂K_(2.5)ZrV(SiO₄)₃F_(0.5); Li₄K₂MnV(SiO₄)₃(OH)₂; Li₃Na₃KTi₂(SiO₄)₃F;K₆V₂(SiO₄)₃(OH)Br; Li₈FeMn(SiO₄)₃F₂; Na₃K_(4.5)MnNi(SiO₄)₃(OH)_(1.5);Li₃Na₂K₂TiV(SiO₄)₃(OH)_(0.5)Cl_(0.5); K₉VCr(SiO₄)₃F₂Cl;Li₄Na₄V₂(SiO₄)₃FBr; Li₄FeMg(SO₄)₃F₂; Na₂KNiCo(SO₄)₃(OH);Na₅MnCa(SO₄)₃F₂Cl; Li₃NaCoBa(SO₄)₃FBr; Li_(2.5)K_(0.5)FeZn(SO₄)₃F;Li₃MgFe(SO₄)₃F₂; Li₂NaCaV(SO₄)₃FCl; Na₄NiMn(SO₄)₃(OH)₂; Na₂KBaFe(SO₄)₃F;Li₂KCuV(SO₄)₃(OH)Br; Li_(1.5)CoPO₄F_(0.5); Li_(1.25)CoPO₄F_(0.25);Li_(1.75)FePO₄F_(0.75); Li_(1.66)MnPO₄F_(0.66);Li_(1.5)Co_(0.75)Ca_(0.25)PO₄F_(0.5);Li_(1.75)Co_(0.8)Mn_(0.2)PO₄F_(0.75);Li_(1.25)F_(0.75)Mg_(0.25)PO₄F_(0.25);Li_(1.66)Co_(0.6)Zn_(0.4)PO₄F_(0.66); KMn₂SiO₄Cl; Li₂VSiO₄(OH)₂;Li₃CoGeO₄F; LiMnSO₄F; NaFe_(0.9)Mg_(0.1)SO₄Cl; LiFeSO₄F; LiMnSO₄OH;KMnSO₄F; Li_(1.75)Mn_(0.8)Mg_(0.2)PO₄F_(0.75); Li₃FeZn(PO₄)F₂;Li_(0.5)V_(0.75)Mg_(0.5)(PO₄)F_(0.75); Li₃V_(0.5)Al_(0.5)(PO₄)F_(3.5);Li_(0.75)VCa(PO₄)F_(1.75); Li₄CuBa(PO₄)F₄;Li_(0.5)V_(0.5)Ca(PO₄)(OH)_(1.5); Li_(1.5)FeMg(PO₄)(OH)Cl;LiFeCoCa(PO₄)(OH)₃F; Li₃CoBa(PO₄)(OH)₂Br₂;Li_(0.75)Mn_(1.5)Al(PO₄)(OH)_(3.75); Li₂Co_(0.75)Mg_(0.25)(PO₄)F;LiNaCo_(0.8)Mg_(0.2)(PO₄)F; NaKCo_(0.5)Mg_(0.5)(PO₄)F;LiNa_(0.5)K_(0.5)Fe_(0.75)Mg_(0.25)(PO₄)F;Li_(1.5)K_(0.5)V_(0.5)Zn_(0.5)(PO₄)F₂; Na₆Fe₂Mg(PS₄)₃(OH₂)Cl;Li₄Mn_(1.5)Co_(0.5)(PO₃F)₃(OH)_(3.5); K₈FeMg(PO₃F)₃F₃Cl₃Li₅Fe₂Mg(SO₄)₃Cl₅; LiTi₂(SO₄)₃Cl, LiMn₂(SO₄)₃F, Li₃Ni₂(SO₄)₃Cl,Li₃Co₂(SO₄)₃F, Li₃Fe₂(SO₄)₃Br, Li₃Mn₂(SO₄)₃F, Li₃MnFe(SO₄)₃F,Li₃NiCo(SO₄)₃Cl; LiMnSO₄F; LiFeSO₄Cl; LiNiSO₄F; LiCoSO₄Cl;LiMn_(1-x)Fe_(x)SO₄F, LiFe_(1-x)Mg_(x)SO₄F; Li₇ZrMn(SiO₄)₃F;Li₇MnCo(SiO₄)₃F; Li₇MnNi(SiO₄)₃F; Li₇VAl(SiO₄)₃F; Li₅MnCo(PO₄)₂(SiO₄)F;Li₄VAl(PO₄)₂(SiO₄)F; Li₄MnV(PO₄)₂(SiO₄)F; Li₄VFe(PO₄)₂(SiO₄)F;Li_(0.6)VPO₄F_(0.6); Li_(0.8)VPO₄F_(0.8); LiVPO₄F; Li₃V₂(PO₄)₂F₃;LiVPO₄Cl; LiVPO₄OH; NaVPO₄F; Na₃V₂(PO₄)₂F₃; LiV_(0.9)Al_(0.1)PO₄F;LiFePO₄F; LiTiPO₄F; LiCrPO₄F; LiFePO₄; LiFe_(0.9)Mg_(0.1)PO₄;LiFe_(0.8)Mg_(0.2)PO₄; LiFe_(0.9)Ca_(0.1)PO₄; LiFe_(0.8)Ca_(0.2)PO₄;LiFe_(0.8)Zn_(0.2)PO₄; Li₃V₂(PO₄)₃; Li₃Fe₂(PO₄)₃; Li₃Mn₂(PO₄)₃;Li₃FeTi(PO₄)₃; Li₃CoMn(PO₄)₃; Li₃FeV(PO₄)₃; Li₃VTi(PO₄)₃; Li₃FeCr(PO₄)₃;Li₃FeMo(PO₄)₃; Li₃FeNi(PO₄)₃; Li₃FeMn(PO₄)₃; Li₃FeAl(PO₄)₃;Li₃FeCo(PO₄)₃; Li₃Ti₂(PO₄)₃; Li₃TiCr(PO₄)₃; Li₃TiMn(PO₄)₃;Li₃TiMo(PO₄)₃; Li₃TiCo(PO₄)₃; Li₃TiAl(PO₄)₃; Li₃TiNi(PO₄)₃;Li₃ZrMnSiP₂O₁₂; Li₃V₂SiP₂O₁₂; Li₃MnVSiP₂O₁₂; Li₃TiVSiP₂O₁₂;Li₃TiCrSiP₂O₁₂; Li_(3.5)AlVSi_(0.5)P_(2.5)O₁₂;Li_(3.5)AlVSi_(0.5)P_(2.5)O₁₂; Li_(2.5)AlCrSi_(0.5)P_(2.5)O₁2;Li_(2.5)V₂P₃O_(11.5)F_(0.5); Li₂V₂P₃O₁₁F; Li_(2.5)VMnP₃O_(11.5)F_(0.5);Li₂V_(0.5)Fe_(1.5)P₃O₁₁F; Li₃V_(0.5)V_(1.5)P₃O_(11.5)F_(0.5);Li₃V₂P₃O₁₁F; Li₃Mn_(0.5)V_(1.5)P₃O₁₁F_(0.5);LiCo_(0.8)Fe_(0.1)Ti_(0.025)Mg_(0.05)PO₄;Li_(1.025)Co_(0.8)Fe_(0.1)Ti_(0.025)Al_(0.025)PO₄;Li_(1.025)Co_(0.8)Fe_(0.1)Ti_(0.025)Mg_(0.025)PO_(3.975)F_(0.025);LiCo_(0.825)Fe_(0.1)Ti_(0.025)Mg_(0.025)PO₄;LiCo_(0.85)Fe_(0.075)Ti_(0.025)Mg_(0.025)PO₄;LiCo_(0.8)Fe_(0.1)Ti_(0.025)Al_(0.025)Mg_(0.025)PO₄,Li_(1.025)Co_(0.8)Fe_(0.1)Ti_(0.025)Mg_(0.05)PO₄,Li_(1.025)Co_(0.8)Fe_(0.1)Ti_(0.025)Al_(0.025)Mg_(0.025)PO₄,LiCo_(0.8)Fe_(0.1)Ti_(0.05)Mg_(0.05)PO₄, and mixtures thereof. Preferredactive materials include LiFePO₄; LiFe_(0.9)Mg_(0.1)PO₄;LiFe_(0.8)Mg_(0.2)PO₄;Li_(1.025)Co_(0.85)Fe_(0.05)Al_(0.025)Mg_(0.05)PO₄,Li_(1.025)Co_(0.80)Fe_(0.10)Al_(0.025)Mg_(0.05)PO₄,Li_(1.025)Co_(0.75)Fe_(0.15)Al_(0.025)Mg_(0.05)PO₄,Li_(1.025)Co_(0.7)(Fe_(0.4)Mn_(0.6))_(0.2)Al_(0.025)Mg_(0.05)PO₄,LiCo_(0.8)Fe_(0.1)Al_(0.025)Ca_(0.05)PO_(3.975)F_(0.025),LiCo_(0.8)Fe_(0.1)Al_(0.025)Mg_(0.05)PO_(3.975)F_(0.025),LiCo_(0.8)Fe_(0.1)Ti_(0.025)Mg_(0.05)PO₄;Li_(1.025)Co_(0.8)Fe_(0.1)Ti_(0.025)Al_(0.025)PO₄;Li_(1.025)Co_(0.8)Fe_(0.1)Ti_(0.025)Mg_(0.025)PO_(3.975)F_(0.025);LiCo_(0.825)Fe_(0.1)Ti_(0.025)Mg_(0.025)PO₄;LiCo_(0.85)Fe_(0.075)Ti_(0.025)Mg_(0.025)PO₄; and mixtures thereof. Aparticularly preferred active material isLiCo_(0.8)Fe_(0.1)Al_(0.025)Mg_(0.05)PO_(3.975)F_(0.025).

Methods of Manufacture:

Active materials of general formula A_(a)M_(b)(XY₄)_(c)Z_(d) are readilysynthesized by reacting starting materials in a solid state reaction,with or without simultaneous oxidation or reduction of the metal speciesinvolved. According to the desired values of a, b, c, and d in theproduct, starting materials are chosen that contain “a” moles of alkalimetal A from all sources, “b” moles of metals M from all sources, “c”moles of phosphate (or other XY₄ species) from all sources, and “d”moles of halide or hydroxide Z, again taking into account all sources.As discussed below, a particular starting material may be the source ofmore than one of the components A, M, XY₄, or Z. Alternatively it ispossible to run the reaction with an excess of one or more of thestarting materials. In such a case, the stoichiometry of the productwill be determined by the limiting reagent among the components A, M,XY₄, and Z. Because in such a case at least some of the startingmaterials will be present in the reaction product mixture, it is usuallydesirable to provide exact molar amounts of all the starting materials.

In one aspect, the moiety XY₄ of the active material comprises asubstituted group represented by X′O_(4-x)Y′_(x), where x is less thanor equal to 1, and preferably less than or equal to about 0.1. Suchgroups may be synthesized by providing starting materials containing, inaddition to the alkali metal and other metals, phosphate or other X′O₄material in a molar amount equivalent to the amount necessary to producea reaction product containing X′O₄. Where Y′ is F, the startingmaterials further comprise a source of fluoride in a molar amountsufficient to substitute F in the product as shown in the formula. Thisis generally accomplished by including at least “x” moles of F in thestarting materials. For embodiments where d>0, the fluoride source isused in a molar limiting quantity such that the fluorine is incorporatedas a Z-moiety. Sources of F include ionic compounds containing fluorideion (F⁻) or hydrogen difluoride ion (HF₂ ⁻). The cation may be anycation that forms a stable compound with the fluoride or hydrogendifluoride anion. Examples include +1, +2, and +3 metal cations, as wellas ammonium and other nitrogen-containing cations. Ammonium is apreferred cation because it tends to form volatile by-products that arereadily removed from the reaction mixture.

Similarly, to make X!O_(4-x)N_(x), starting materials are provided thatcontain “x” moles of a source of nitride ion. Sources of nitride areamong those known in the art including nitride salts such as Li₃N and(NH₄)₃N.

It is preferred to synthesize the active materials of the inventionusing stoichiometric amounts of the starting materials, based on thedesired composition of the reaction product expressed by the subscriptsa, b, c, and d above. Alternatively it is possible to run the reactionwith a stoichiometric excess of one or more of the starting materials.In such a case, the stoichiometry of the product will be determined bythe limiting reagent among the components. There will also be at leastsome unreacted starting material in the reaction product mixture.Because such impurities in the active materials are generallyundesirable (with the exception of reducing carbon, discussed below), itis generally preferred to provide relatively exact molar amounts of allthe starting materials.

The sources of components A, M, phosphate (or other XY₄ moiety) andoptional sources of F or N discussed above, and optional sources of Zmay be reacted together in the solid state while heating for a time andat a temperature sufficient to make a reaction product. The startingmaterials are provided in powder or particulate form. The powders aremixed together with any of a variety of procedures, such as by ballmilling, blending in a mortar and pestle, and the like. Thereafter themixture of powdered starting materials may be compressed into a pelletand/or held together with a binder material to form a closely coheringreaction mixture. The reaction mixture is heated in an oven, generallyat a temperature of about 400° C. or greater until a reaction productforms.

Another means for carrying out the reaction at a lower temperature is ahydothermal method. In a hydrothermal reaction, the starting materialsare mixed with a small amount of a liquid such as water, and placed in apressurized bomb. The reaction temperature is limited to that which canbe achieved by heating the liquid water under pressure, and theparticular reaction vessel used.

The reaction may be carried out without redox, or if desired, underreducing or oxidizing conditions. When the reaction is carried out underreducing conditions, at least some of the transition metals in thestarting materials are reduced in oxidation state. When the reaction isdone without redox, the oxidation state of the metal or mixed metals inthe reaction product is the same as in the starting materials. Oxidizingconditions may be provided by running the reaction in air. Thus, oxygenfrom the air is used to oxidize the starting material containing thetransition metal.

The reaction may also be carried out with reduction. For example, thereaction may be carried out in a reducing atmosphere such as hydrogen,ammonia, methane, or a mixture of reducing gases. Alternatively, thereduction may be carried out in situ by including in the reactionmixture a reductant that will participate in the reaction to reduce ametal M, but that will produce by-products that will not interfere withthe active material when used later in an electrode or anelectrochemical cell. The reductant is described in greater detailbelow.

Sources of alkali metal include any of a number of salts or ioniccompounds of lithium, sodium, potassium, rubidium or cesium. Lithium,sodium, and potassium compounds are preferred, with lithium beingparticularly preferred. Preferably, the alkali metal source is providedin powder or particulate form. A wide range of such materials is wellknown in the field of inorganic chemistry. Examples include the lithium,sodium, and/or potassium fluorides, chlorides, bromides, iodides,nitrates, nitrites, sulfates, hydrogen sulfates, sulfites, bisulfites,carbonates, bicarbonates, borates, phosphates, hydrogen ammoniumphosphates, dihydrogen ammonium phosphates, silicates, antimonates,arsenates, germinates, oxides, acetates, oxalates, and the like.Hydrates of the above compounds may also be used, as well as mixtures.In particular, the mixtures may contain more than one alkali metal sothat a mixed alkali metal active material will be produced in thereaction.

Sources of metals M, M¹, M², M³, and M⁴ include salts or compounds ofany of the transition metals, alkaline earth metals, or lanthanidemetals, as well as of non-transition elements such as boron, aluminum,gallium, indium, thallium, germanium, tin, lead, antimony, and bismuth.The metal salts or compounds include fluorides, chlorides, bromides,iodides, nitrates, nitrites, sulfates, hydrogen sulfates, sulfites,bisulfites, carbonates, bicarbonates, borates, phosphates, hydrogenammonium phosphates, dihydrogen ammonium phosphates, silicates,antimonates, arsenates, germanates, oxides, hydroxides, acetates,oxalates, and the like. Hydrates may also be used. The metal M in thestarting material may have any oxidation state, depending on theoxidation state required in the desired product and the oxidizing orreducing conditions contemplated, as discussed below. In particular, thecobalt and iron of the active materials may be provided by startingmaterials with Co⁺², Co⁺³, Fe⁺², or Fe⁺³. The metal sources are chosenso that at least one metal in the final reaction product is capable ofbeing in an oxidation state higher than it is in the reaction product.In a preferred embodiment, the metal sources also include a +2non-transition metal. Also preferably, at least one metal source is asource of a +3 non-transition metal. In embodiments comprising Ti, asource of Ti is provided in the starting materials and the compounds aremade using reducing or non-reducing conditions depending on the othercomponents of the product and the desired oxidation state of Ti andother metals in the final product. Suitable Ti-containing precursorsinclude TiO₂, Ti₂O₃, and TiO.

Sources of the desired starting material anions, such as phosphates,halides and hydroxides, are provided by a number of salts or compoundscontaining positively charged cations in addition to a source ofphosphate (or other XY₄ species), halide, or hydroxide. Such cationsinclude metal ions such as the alkali metals, alkaline metals,transition metals, or other non-transition elements, as well as complexcations such as ammonium or quaternary ammonium. The phosphate anion insuch compounds may be phosphate, hydrogen ammonium phosphate, ordihydrogen ammonium phosphate. As with the alkali metal source and metalsource discussed above, the phosphate or other XY₄ species, halide andhydroxide starting materials are preferably provided in particulate orpowder form. Hydrates of any of the above may be used, as can mixturesof the above.

As noted above, the active materials A_(a)M_(b)(XY₄)_(c)Z_(d) of theinvention can contain a mixture of alkali metals A, a mixture of metalsM, a phosphate group representative of the XY₄ group in the formula and,optionally, a halide or hydroxide Z. In another aspect of the invention,the phosphate group can be completely or partially substituted by anumber of other XY₄ moieties, which will also be referred to as“phosphate replacements” or “modified phosphates.” Thus, activematerials are provided according to the invention wherein the XY₄ moietyis a phosphate group that is completely or partially replaced by suchmoieties as sulfate (SO₄)²⁻, monofluoromonophosphate, (PO₃F)²⁻,difluoromonophosphate (PO₂F)²⁻, silicate (SiO₄)⁴⁻, arsenate, antimonate,and germanate. Analogues of the above oxygenate anions where some or allof the oxygen is replaced by sulfur are also useful in the activematerials of the invention, with the exception that the sulfate groupmay not be completely substituted with sulfur. For examplethiomonophosphates may also be used as a complete or partial replacementfor phosphate in the active materials of the invention. Suchthiomonophosphates include the anions (PO₃S)³⁻, (PO₂S₂)³⁻, (POS₃)³⁻, and(PS₄)³⁻. They are most conveniently available as the sodium, lithium, orpotassium derivative.

To synthesize the active materials containing the modified phosphatemoieties, it is usually possible to substitute all or preferably onlypart of the phosphate compounds discussed above with a source of thereplacement anion. The replacement is considered on a stoichiometricbasis. Starting materials providing the source of the replacement anionsare provided along with the other starting materials as discussed above.Synthesis of the active materials containing the modified phosphategroups proceeds as discussed above, either without redox or underoxidizing or reducing conditions. As was the case with the phosphatecompounds, the compound containing the modified or replacement phosphategroup or groups may also be a source of other components of the activematerials. For example, the alkali metal and/or any of the other metalsmay be a part of the modified phosphate compound.

Non-limiting examples of sources of monofluoromonophosphates includeNa₂PO₃F, K₂PO₃F, (NH₄)₂PO₃F.H₂O, LiNaPO₃F.H₂O, LiKPO₃F, LiNH₄PO₃F,NaNH₄PO₃F, NaK₃(PO₃F)₂ and CaPO₃F.2H₂O. Representative examples ofsources of difluoromonophosphate compounds include, without limitation,NH₄PO₂F₂, NaPO₂F₂, KPO₂F₂, Al(PO₂F₂)₃, and Fe(PO₂F₂)₃.

When it is desired to partially or completely replace phosphorous in theactive materials with silicon, it is possible to use a wide variety ofsilicates and other silicon containing compounds. Thus, useful sourcesof silicon in the active materials of the invention includeorthosilicates, pyrosilicates, cyclic silicate anions such as (Si₃O₉)⁶⁻,(Si₆O₁₈)¹²⁻ and the like, and pyrocenes represented by the formula[(SiO₃)²⁻]_(n), for example LiAl(SiO₃)₂. Silica or SiO₂ may also beused. Partial substitution of silicate for phosphate is illustrated inExample 4.

Representative arsenate compounds that may be used to prepare the activematerials of the invention include H₃AsO₄ and salts of the anions[H₂AsO₄]⁻ and [HAsO₄]²⁻. Sources of antimonate in the active materialscan be provided by antimony-containing materials such as Sb₂O₅,M^(I)SbO₃ where M^(I) is a metal having oxidation state +1, M^(III)SbO₄where M^(III) is a metal having an oxidation state of +3, andM^(II)Sb₂O₇ where M^(II) is a metal having an oxidation state of +2.Additional sources of antimonate include compounds such as Li₃SbO₄,NH₄H₂SbO₄, and other alkali metal and/or ammonium mixed salts of the[SbO₄]³⁻ anion.

Sources of sulfate compounds that can be used to partially or completelyreplace phosphorous in the active materials with sulfur include alkalimetal and transition metal sulfates and bisulfates as well as mixedmetal sulfates such as (NH₄)₂Fe(SO₄)₂, NH₄Fe(SO₄)₂ and the like.Finally, when it is desired to replace part or all of the phosphorous inthe active materials with germanium, a germanium containing compoundsuch as GeO₂ may be used.

To prepare the active materials containing the modified phosphategroups, it generally suffices to choose the stoichiometry of thestarting materials based on the desired stoichiometry of the modifiedphosphate groups in the final product and react the starting materialstogether according to the procedures described above with respect to thephosphate materials. Naturally, partial or complete substitution of thephosphate group with any of the above modified or replacement phosphategroups will entail a recalculation of the stoichiometry of the requiredstarting materials.

A starting material may provide more than one of the components A, M,XY₄, and Z, as is evident in the list above. In various embodiments ofthe invention, starting materials are provided that combine, forexample, the metal and the phosphate, thus requiring only the alkalimetal to be added. In one embodiment, a starting material is providedthat contains alkali metal, metal, and phosphate. As a general rule,there is flexibility to select starting materials containing any of thecomponents of alkali metal A, metal M, and phosphate (or other XY₄moiety), as well as halide or hydroxide Z, depending on availability.Combinations of starting materials providing each of the components mayalso be used.

In general, any anion may be combined with the alkali metal cation toprovide the alkali metal source starting material, or with a metal Mcation to provide a metal starting material. Likewise, any cation may becombined with the halide or hydroxide anion to provide the source of Zcomponent starting material, and any cation may be used as counterion tothe phosphate or similar XY₄ component. It is preferred, however, toselect starting materials with counterions that give rise to theformation of volatile by-products during the solid state reaction. Thus,it is desirable to choose ammonium salts, carbonates, bicarbonates,oxides, hydroxides, and the like where possible. Starting materials withthese counterions tend to form volatile by-products such as water,ammonia, and carbon dioxide, which can be readily removed from thereaction mixture. Similarly, sulfur-containing anions such as sulfate,bisulfate, sulfite, bisulfite and the like tend to result in volatilesulfur oxide by-products. Nitrogen-containing anions such as nitrate andnitrite also tend to give volatile NO_(x) by-products.

As noted above, the reactions may be carried out without reduction, orin the presence of a reductant. In one aspect, the reductant, whichprovides reducing power for the reactions, may be provided in the formof a reducing carbon by including a source of elemental carbon alongwith the other particulate starting materials. In this case, thereducing power is provided by simultaneous oxidation of carbon to eithercarbon monoxide or carbon dioxide.

The starting materials containing transition metal compounds are mixedtogether with carbon, which is included in an amount sufficient toreduce the metal ion of one or more of the metal-containing startingmaterials without full reduction to an elemental metal state. (Excessquantities of the reducing carbon may be used to enhance productquality.) An excess of carbon, remaining after the reaction, functionsas a conductive constituent in the ultimate electrode formulation. Thisis an advantage since such remaining carbon is very intimately mixedwith the product active material. Accordingly, large quantities ofexcess carbon, on the order of 100% excess carbon or greater are useablein the process. In a preferred embodiment, the carbon present duringcompound formation is intimately dispersed throughout the precursor andproduct. This provides many advantages, including the enhancedconductivity of the product. In a preferred embodiment, the presence ofcarbon particles in the starting materials also provides nucleationsites for the production of the product crystals.

Alternatively or in addition, the source of reducing carbon may beprovided by an organic material. The organic material is characterizedas containing carbon and at least one other element, preferablyhydrogen. The organic material generally forms a decomposition product,referred to herein as a carbonaceous material, upon heating under theconditions of the reaction. Without being bound by theory,representative decomposition processes that can lead to the formation ofthe carbonaceous material include pyrolization, carbonization, coking,destructive distillation, and the like. These process names, as well asthe term thermal decomposition, are used interchangeably in thisapplication to refer to the process by which a decomposition productcapable of acting as a reductant is formed upon heating of a reactionmixture containing an organic material.

A typical decomposition product contains carbonaceous material. Duringreaction in a preferred embodiment, at least a portion of thecarbonaceous material formed participates as a reductant. That portionthat participates as reductant may form a volatile by-product such asdiscussed below. Any volatile by-product formed tends to escape from thereaction mixture so that it is not incorporated into the reactionproduct.

Although the invention is understood not to be limited as to themechanism of action of the organic precursor material, it believed thatthe carbonaceous material formed from decomposition of the organicmaterial provides reducing power similar to that provided by elementalcarbon discussed above. For example, the carbonaceous material mayproduce carbon monoxide or carbon dioxide, depending on the temperatureof the reaction.

In a preferred embodiment, some of the organic material providingreducing power is oxidized to a non-volatile component, such as forexample, oxygen-containing carbon materials such as alcohols, ketones,aldehydes, esters, and carboxylic acids and anhydrides. Suchnon-volatile by-products, as well as any carbonaceous material that doesnot participate as reductant (for example, any present in stoichiometricexcess or any that does not otherwise react) will tend to remain in thereaction mixture along with the other reaction products, but will not besignificantly covalently incorporated.

The carbonaceous material prepared by heating the organic precursormaterial will preferably be enriched in carbon relative to the mole percent carbon present in the organic material. The carbonaceous materialpreferably contains from about 50 up to about 100 mole percent carbon.

While in some embodiments the organic precursor material forms acarbonaceous decomposition product that acts as a reductant as discussedabove with respect to elemental carbon, in other embodiments a portionof the organic material may participate as reductant without firstundergoing a decomposition. The invention is not limited by the exactmechanism or mechanisms of the underlying reduction processes.

As with elemental carbon, reactions with the organic precursor materialare conveniently carried out by combining starting materials andheating. The starting materials include at least one transition metalcompound as noted above. For convenience, it is preferred to carry outthe decomposition of the organic material and the reduction of atransition metal in one step. In this embodiment, the organic materialdecomposes in the presence of the transition metal compound to form adecomposition product capable of acting as a reductant, which reactswith the transition metal compound to form a reduced transition metalcompound. In another embodiment, the organic material may be decomposedin a separate step to form a decomposition product. The decompositionproduct may then be combined with a transition metal compound to form amixture. The mixture may then be heated for a time and at a temperaturesufficient to form a reaction product comprising a reduced transitionmetal compound.

The organic precursor material may be any organic material capable ofundergoing pyrolysis or carbonization, or any other decompositionprocess that leads to a carbonaceous material rich in carbon. Suchprecursors include in general any organic material, i.e., compoundscharacterized by containing carbon and at least one other element.Although the organic material may be a perhalo compound containingessentially no carbon-hydrogen bonds, typically the organic materialscontain carbon and hydrogen. Other elements, such as halogens, oxygen,nitrogen, phosphorus, and sulfur, may be present in the organicmaterial, as long as they do not significantly interfere with thedecomposition process or otherwise prevent the reductions from beingcarried out. Precursors include organic hydrocarbons, alcohols, esters,ketones, aldehydes, carboxylic acids, sulfonates, and ethers. Preferredprecursors include the above species containing aromatic rings,especially the aromatic hydrocarbons such as tars, pitches, and otherpetroleum products or fractions. As used here, hydrocarbon refers to anorganic compound made up of carbon and hydrogen, and containing nosignificant amounts of other elements. Hydrocarbons may containimpurities having some heteroatoms. Such impurities might result, forexample, from partial oxidation of a hydrocarbon or incompleteseparation of a hydrocarbon from a reaction mixture or natural sourcesuch as petroleum.

Other organic precursor materials include sugars and othercarbohydrates, including derivatives and polymers. Examples of polymersinclude starch, cellulose, and their ether or ester derivatives. Otherderivatives include the partially reduced and partially oxidizedcarbohydrates discussed below. On heating, carbohydrates readilydecompose to form carbon and water. The term carbohydrates as used hereencompasses the D-, L-, and DL-forms, as well as mixtures, and includesmaterial from natural or synthetic sources.

In one sense as used in the invention, carbohydrates are organicmaterials that can be written with molecular formula (C)_(m)(H₂O)_(n),where m and n are integers. For simple hexose or pentose sugars, m and nare equal to each other. Examples of hexoses of formula C₆H₁₂O₆ includeallose, altose, glucose, mannose, gulose, inose, galactose, talose,sorbose, tagatose, and fructose. Pentoses of formula C₅H₁₀O₅ includeribose, arabinose, and xylose. Tetroses include erythrose and threose,while glyceric aldehyde is a triose. Other carbohydrates include thetwo-ring sugars (di-saccharides) of general formula C₁₂H₂₂O₁₁. Examplesinclude sucrose, maltose, lactose, trehalose, gentiobiose, cellobiose,and melibiose. Three-ring (trisaccharides such as raffinose) and higheroligomeric and polymer carbohydrates may also be used. Examples includestarch and cellulose. As noted above, the carbohydrates readilydecompose to carbon and water when heated to a sufficiently hightemperature. The water of decomposition tends to turn to steam under thereaction conditions and volatilize.

It will be appreciated that other materials will also tend to readilydecompose to H₂O and a material very rich in carbon. Such materials arealso intended to be included in the term “carbohydrate” as used in theinvention. Such materials include slightly reduced carbohydrates such asglycerol, sorbitol, mannitol, iditol, dulcitol, talitol, arabitol,xylitol, and adonitol, as well as “slightly oxidized” carbohydrates suchas gluconic, mannonic, glucuronic, galacturonic, mannuronic, saccharic,manosaccharic, ido-saccharic, mucic, talo-mucic, and allo-mucic acids.The formula of the slightly oxidized and the slightly reducedcarbohydrates is similar to that of the carbohydrates.

A preferred carbohydrate is sucrose. Under the reaction conditions,sucrose melts at about 150-180° C. Preferably, the liquid melt tends todistribute itself among the starting materials. At temperatures aboveabout 450° C., sucrose and other carbohydrates decompose to form carbonand water. The as-decomposed carbon powder is in the form of freshamorphous fine particles with high surface area and high reactivity.

The organic precursor material may also be an organic polymer. Organicpolymers include polyolefins such as polyethylene and polypropylene,butadiene polymers, isoprene polymers, vinyl alcohol polymers, furfurylalcohol polymers, styrene polymers including polystyrene,polystyrene-polybutadiene and the like, divinylbenzene polymers,naphthalene polymers, phenol condensation products including thoseobtained by reaction with aldehyde, polyacrylonitrile, polyvinylacetate, as well as cellulose starch and esters and ethers thereofdescribed above.

In some embodiments, the organic precursor material is a solid availablein particulate form. Particulate materials may be combined with theother particulate starting materials and reacted by heating according tothe methods described above.

In other embodiments, the organic precursor material may be a liquid. Insuch cases, the liquid precursor material is combined with the otherparticulate starting materials to form a mixture. The mixture is heated,whereupon the organic material forms a carbonaceous material in situ.The reaction proceeds with carbothermal reduction. The liquid precursormaterials may also advantageously serve or function as a binder in thestarting material mixture as noted above.

Reducing carbon is preferably used in the reactions in stoichiometricexcess. To calculate relative molar amounts of reducing carbon, it isconvenient to use an “equivalent” weight of the reducing carbon, definedas the weight per gram-mole of carbon atom. For elemental carbons suchas carbon black, graphite, and the like, the equivalent weight is about12 g/equivalent. For other organic materials, the equivalent weight pergram-mole of carbon atoms is higher. For example, hydrocarbons have anequivalent weight of about 14 g/equivalent. Examples of hydrocarbonsinclude aliphatic, alicyclic, and aromatic hydrocarbons, as well aspolymers containing predominantly or entirely carbon and hydrogen in thepolymer chain. Such polymers include polyolefins and aromatic polymersand copolymers, including polyethylenes, polypropylenes, polystyrenes,polybutadienes, and the like. Depending on the degree of unsaturation,the equivalent weight may be slightly above or below 14.

For organic materials having elements other than carbon and hydrogen,the equivalent weight for the purpose of calculating a stoichiometricquantity to be used in the reactions is generally higher than 14. Forexample, in carbohydrates it is about 30 g/equivalent. Examples ofcarbohydrates include sugars such as glucose, fructose, and sucrose, aswell as polymers such as cellulose and starch.

Although the reactions may be carried out in oxygen or air, the heatingis preferably conducted under an essentially non-oxidizing atmosphere.The atmosphere is essentially non-oxidizing so as not to interfere withthe reduction reactions taking place. An essentially non-oxidizingatmosphere can be achieved through the use of vacuum, or through the useof inert gases such as argon, nitrogen, and the like. Although oxidizinggas (such as oxygen or air), may be present, it should not be at sogreat a concentration that it interferes with the carbothermal reductionor lowers the quality of the reaction product. It is believed that anyoxidizing gas present will tend to react with the reducing carbon andlower the availability of the carbon for participation in the reaction.To some extent, such a contingency can be anticipated and accommodatedby providing an appropriate excess of reducing carbon as a startingmaterial. Nevertheless, it is generally preferred to carry out thecarbothermal reduction in an atmosphere containing as little oxidizinggas as practical.

In a preferred embodiment, reduction is carried out in a reducingatmosphere in the presence of a reductant as discussed above. The term“reducing atmosphere” as used herein means a gas or mixture of gasesthat is capable of providing reducing power for a reaction that iscarried out in the atmosphere. Reducing atmospheres preferably containone or more so-called reducing gases. Examples of reducing gases includehydrogen, carbon monoxide, methane, and ammonia, as well as mixturesthereof. Reducing atmospheres also preferably have little or nooxidizing gases such as air or oxygen. If any oxidizing gas is presentin the reducing atmosphere, it is preferably present at a level lowenough that it does not significantly interfere with any reductionprocesses taking place.

The stoichiometry of the reduction can be selected along with therelative stoichiometric amounts of the starting components A, M, PO₄ (orother XY₄ moiety), and Z. It is usually easier to provide the reducingagent in stoichiometric excess and remove the excess, if desired, afterthe reaction. In the case of the reducing gases and the use of reducingcarbon such as elemental carbon or an organic material, any excessreducing agent does not present a problem. In the former case, the gasis volatile and is easily separated from the reaction mixture, while inthe latter, the excess carbon in the reaction product does not harm theproperties of the active material, particularly in embodiments wherecarbon is added to the active material to form an electrode material foruse in the electrochemical cells and batteries of the invention.Conveniently also, the by-products carbon monoxide or carbon dioxide (inthe case of carbon) or water (in the case of hydrogen) are readilyremoved from the reaction mixture.

When using a reducing atmosphere, it is difficult to provide less thanan excess of reducing gas such as hydrogen. Under such as a situation,it is preferred to control the stoichiometry of the reaction by theother limiting reagents. Alternatively the reduction may be carried outin the presence of reducing carbon such as elemental carbon.Experimentally, it would be possible to use precise amounts of reductantcarbon to make products of a chosen stoichiometry. However, it ispreferred to carry out the carbothermal reduction in a molar excess ofcarbon. As with the reducing atmosphere, this is easier to doexperimentally, and it leads to a product with excess carbon dispersedinto the reaction product, which as noted above provides a useful activeelectrode material.

Before reacting the mixture of starting materials, the particles of thestarting materials are intermingled. Preferably, the starting materialsare in particulate form, and the intermingling results in an essentiallyhomogeneous powder mixture of the precursors. In one embodiment, theprecursor powders are dry-mixed using, for example, a ball mill. Thenthe mixed powders are pressed into pellets. In another embodiment, theprecursor powders are mixed with a binder. The binder is preferablyselected so as not to inhibit reaction between particles of the powders.Preferred binders decompose or evaporate at a temperature less than thereaction temperature. Examples include mineral oils, glycerol, andpolymers that decompose or carbonize to form a carbon residue before thereaction starts, or that evaporate before the reaction starts. In oneembodiment, the binders used to hold the solid particles also functionas sources of reducing carbon, as described above. In still anotherembodiment, intermingling is accomplished by forming a wet mixture usinga volatile solvent and then the intermingled particles are pressedtogether in pellet form to provide good grain-to-grain contact.

The mixture of starting materials is heated for a time and at atemperature sufficient to form an inorganic transition metal compoundreaction product. If the starting materials include a reducing agent,the reaction product is a transition metal compound having at least onetransition metal in a lower oxidation state relative to its oxidationstate in the starting materials.

Preferably, the particulate starting materials are heated to atemperature below the melting point of the starting materials.Preferably, at least a portion of the starting material remains in thesolid state during the reaction.

The temperature should preferably be about 400° C. or greater, anddesirably about 450° C. or greater, and preferably about 500° C. orgreater, and generally will proceed at a faster rate at highertemperatures. The various reactions involve production of CO or CO₂ asan effluent gas. The equilibrium at higher temperature favors COformation. Some of the reactions are more desirably conducted attemperatures greater than about 600° C.; most desirably greater thanabout 650° C.; preferably about 700° C. or greater; more preferablyabout 750° C. or greater. Suitable ranges for many reactions are fromabout 700 to about 950° C., or from about 700 to about 800° C.

Generally, the higher temperature reactions produce CO effluent and thestoichiometry requires more carbon be used than the case where CO₂effluent is produced at lower temperature. This is because the reducingeffect of the C to CO₂ reaction is greater than the C to CO reaction.The C to CO₂ reaction involves an increase in carbon oxidation state of+4 (from 0 to 4) and the C to CO reaction involves an increase in carbonoxidation state of +2 (from ground state zero to 2). Here, highertemperature generally refers to a range of about 650° C. to about 1000°C. and lower temperature refers to up to about 650° C. Temperatureshigher than about 1200° C. are not thought to be needed.

In one embodiment, the methods of this invention utilize the reducingcapabilities of carbon in a unique and controlled manner to producedesired products having structure and alkali metal content suitable foruse as electrode active materials. The advantages are at least in partachieved by the reductant, carbon, having an oxide whose free energy offormation becomes more negative as temperature increases. Such oxide ofcarbon is more stable at high temperature than at low temperature. Thisfeature is used to produce products having one or more metal ions in areduced oxidation state relative to the precursor metal ion oxidationstate.

Referring back to the discussion of temperature, at about 700° C. boththe carbon to carbon monoxide and the carbon to carbon dioxide reactionsare occurring. At closer to about 600° C. the C to CO₂ reaction is thedominant reaction. At closer to about 800° C. the C to CO reaction isdominant. Since the reducing effect of the C to CO₂ reaction is greater,the result is that less carbon is needed per atomic unit of metal to bereduced. In the case of carbon to carbon monoxide, each atomic unit ofcarbon is oxidized from ground state zero to plus 2. Thus, for eachatomic unit of metal ion (M) which is being reduced by one oxidationstate, one half atomic unit of carbon is required. In the case of thecarbon to carbon dioxide reaction, one quarter atomic unit of carbon isstoichiometrically required for each atomic unit of metal ion (M) whichis reduced by one oxidation state, because carbon goes from ground statezero to a plus 4 oxidation state. These same relationships apply foreach such metal ion being reduced and for each unit reduction inoxidation state desired.

The starting materials may be heated at ramp rates from a fraction of adegree up to about 10° C. per minute. Higher or lower ramp rates may bechosen depending on the available equipment, desired turnaround, andother factors. It is also possible to place the starting materialsdirectly into a pre-heated oven. Once the desired reaction temperatureis attained, the reactants (starting materials) are held at the reactiontemperature for a time sufficient for reaction to occur. Typically thereaction is carried out for several hours at the final reactiontemperature. The heating is preferably conducted under non-oxidizing orinert gas such as argon or vacuum, or in the presence of a reducingatmosphere.

After reaction, the products are preferably cooled from the elevatedtemperature to ambient (room) temperature (i.e., about 10° C. to about40° C.). The rate of cooling may vary according to a number of factorsincluding those discussed above for heating rates. For example, thecooling may be conducted at a rate similar to the earlier ramp rate.Such a cooling rate has been found to be adequate to achieve the desiredstructure of the final product. It is also possible to quench theproducts to achieve a higher cooling rate, for example on the order ofabout 100° C./minute.

The general aspects of the above synthesis routes are applicable to avariety of starting materials. The metal compounds may be reduced in thepresence of a reducing agent, such as hydrogen or carbon. The sameconsiderations apply to other metal and phosphate containing startingmaterials. The thermodynamic considerations such as ease of reduction ofthe selected starting materials, the reaction kinetics, and the meltingpoint of the salts will cause adjustment in the general procedure, suchas the amount of reducing agent, the temperature of the reaction, andthe dwell time.

Electrodes:

The present invention also provides electrodes comprising an electrodeactive material of the present invention. In a preferred embodiment, theelectrodes of the present invention comprise an electrode activematerial of this invention, a binder; and an electrically conductivecarbonaceous material.

In a preferred embodiment, the electrodes of this invention comprise:

-   -   (1) from about 25% to about 95%, more preferably from about 50%        to about 90%, active material;    -   (2) from about 2% to about 95% electrically conductive material        (e.g., carbon black); and    -   (3) from about 3% to about 20% binder chosen to hold all        particulate materials in contact with one another without        degrading ionic conductivity.

(Unless stated otherwise, all percentages herein are by weight.)Cathodes of this invention preferably comprise from about 50% to about90% of active material, about 5% to about 30% of the electricallyconductive material, and the balance comprising binder. Anodes of thisinvention preferably comprise from about 50% to about 95% by weight ofthe electrically conductive material (e.g., a preferred graphite), withthe balance comprising binder.

Electrically conductive materials among those useful herein includecarbon black, graphite, powdered nickel, metal particles, conductivepolymers (e.g., characterized by a conjugated network of double bondslike polypyrrole and polyacetylene), and mixtures thereof. Bindersuseful herein preferably comprise a polymeric material and extractableplasticizer suitable for forming a bound porous composite. Preferredbinders include halogenated hydrocarbon polymers (such aspoly(vinylidene chloride) and poly((dichloro-1,4-phenylene)ethylene),fluorinated urethanes, fluorinated epoxides, fluorinated acrylics,copolymers of halogenated hydrocarbon polymers, epoxides, ethylenepropylene diamine termonomer (EPDM), ethylene propylene diaminetermonomer (EPDM), polyvinylidene difluoride (PVDF), hexafluoropropylene(HFP), ethylene acrylic acid copolymer (EAA), ethylene vinyl acetatecopolymer (EVA), EAA/EVA copolymers, PVDF/HFP copolymers, and mixturesthereof.

In a preferred process for making an electrode, the electrode activematerial is mixed into a slurry with a polymeric binder compound, asolvent, a plasticizer, and optionally the electroconductive material.The active material slurry is appropriately agitated, and then thinlyapplied to a substrate via a doctor blade. The substrate can be aremovable substrate or a functional substrate, such as a currentcollector (for example, a metallic grid or mesh layer) attached to oneside of the electrode film. In one embodiment, heat or radiation isapplied to evaporate the solvent from the electrode film, leaving asolid residue. The electrode film is further consolidated, where heatand pressure are applied to the film to sinter and calendar it. Inanother embodiment, the film may be air-dried at moderate temperature toyield self-supporting films of copolymer composition. If the substrateis of a removable type it is removed from the electrode film, andfurther laminated to a current collector. With either type of substrateit may be necessary to extract the remaining plasticizer prior toincorporation into the battery cell.

Batteries:

The batteries of the present invention comprise:

-   -   (1) a first electrode comprising an active material of the        present invention;    -   (2) a second electrode which is a counter-electrode to said        first electrode; and    -   (3) an electrolyte between said electrodes.

The electrode active material of this invention may comprise the anode,the cathode, or both. Preferably, the electrode active materialcomprises the cathode.

The active material of the second, counter-electrode is any materialcompatible with the electrode active material of this invention. Inembodiments where the electrode active material comprises the cathode,the anode may comprise any of a variety of compatible anodic materialswell known in the art, including lithium, lithium alloys, such as alloysof lithium with aluminum, mercury, manganese, iron, zinc, andintercalation based anodes such as those employing carbon, tungstenoxides, and mixtures thereof. In a preferred embodiment, the anodecomprises:

-   -   (1) from about 0% to about 95%, preferably from about 25% to        about 95%, more preferably from about 50% to about 90%, of an        insertion material;    -   (2) from about 2% to about 95% electrically conductive material        (e.g., carbon black); and    -   (3) from about 3% to about 20% binder chosen to hold all        particulate materials in contact with one another without        degrading ionic conductivity.

In a particularly preferred embodiment, the anode comprises from about50% to about 90% of an insertion material selected from the group activematerial from the group consisting of metal oxides (particularlytransition metal oxides), metal chalcogenides, and mixtures thereof. Inanother preferred embodiment, the anode does not contain an insertionactive, but the electrically conductive material comprises an insertionmatrix comprising carbon, graphite, cokes, mesocarbons and mixturesthereof. One preferred anode intercalation material is carbon, such ascoke or graphite, which is capable of forming the compound Li_(x)C.Insertion anodes among those useful herein are described in U.S. Pat.No. 5,700,298, Shi et al., issued Dec. 23, 1997; U.S. Pat. No.5,712,059, Barker et al., issued Jan. 27, 1998; U.S. Pat. No. 5,830,602,Barker et al., issued Nov. 3, 1998; and U.S. Pat. No. 6,103,419, Saidiet al., issued Aug. 15, 2000; all of which are incorporated by referenceherein.

In embodiments where the electrode active material comprises the anode,the cathode preferably comprises:

-   -   (1) from about 25% to about 95%, more preferably from about 50%        to about 90%, active material;    -   (2) from about 2% to about 95% electrically conductive material        (e.g., carbon black); and    -   (3) from about 3% to about 20% binder chosen to hold all        particulate materials in contact with one another without        degrading ionic conductivity.

Active materials useful in such cathodes include electrode activematerials of this invention, as well as metal oxides (particularlytransition metal oxides), metal chalcogenides, and mixtures thereof.Other active materials include lithiated transition metal oxides such asLiCoO₂, LiNiO₂, and mixed transition metal oxides such asLiCo_(1-m)Ni_(m)O₂, where 0<m<1. Another preferred active materialincludes lithiated spinel active materials exemplified by compositionshaving a structure of LiMn₂O₄, as well as surface treated spinels suchas disclosed in U.S. Pat. No. 6,183,718, Barker et al., issued Feb. 6,2001, incorporated by reference herein. Blends of two or more of any ofthe above active materials may also be used. The cathode mayalternatively further comprise a basic compound to protect againstelectrode degradation as described in U.S. Pat. No. 5,869,207, issuedFeb. 9, 1999, incorporated by reference herein.

The batteries of this invention also comprise a suitable electrolytethat provides a physical separation but allows transfer of ions betweenthe cathode and anode. The electrolyte is preferably a material thatexhibits high ionic conductivity, as well as having insular propertiesto prevent self-discharging during storage. The electrolyte can beeither a liquid or a solid. A liquid electrolyte comprises a solvent andan alkali metal salt that together form an ionically conducting liquid.So called “solid electrolytes” contain in addition a matrix materialthat is used to separate the electrodes.

One preferred embodiment is a solid polymeric electrolyte, made up of asolid polymeric matrix and a salt homogeneously dispersed via a solventin the matrix. Suitable solid polymeric matrices include those wellknown in the art and include solid matrices formed from organicpolymers, inorganic polymers or a solid matrix-forming monomer and frompartial polymers of a solid matrix forming monomer.

In another variation, the polymer, solvent and salt together form a gelwhich maintains the electrodes spaced apart and provides the ionicconductivity between electrodes. In still another variation, theseparation between electrodes is provided by a glass fiber mat or othermatrix material and the solvent and salt penetrate voids in the matrix.

The electrolytes of the present invention comprise a salt dissolved in amixture of an alkylene carbonate and a cyclic ester. Preferably, thesalt of the electrolyte is a lithium or sodium salt. Such salts amongthose useful herein include LiAsF₆, LiPF₆, LiClO₄, LiB(C₆H₅)₄, LiAICI₄,LiBr, LiBF₄, LiSO₃CF₃, LiN(SO₂CF₃)₂, LiN(SO₂C₂F₅)₂, and mixturesthereof, as well as sodium analogs, with the less toxic salts beingpreferable. The salt content is preferably from about 5% to about 65%,preferably from about 8% to about 35% (by weight of electrolyte). Apreferred salt is LiBF₄. In a preferred embodiment, the LiBF₄ is presentat a molar concentration of from 0.5M to 3M, preferably 1.0M to 2.0M,and most preferably about 1.5M. Electrolyte compositions comprisingsalts among those useful herein are described in U.S. Pat. No.5,418,091, Gozdzetal., issued May 23, 1995; U.S. Pat. No. 5,508,130,Golovin, issued Apr. 16, 1996; U.S. Pat. No. 5,541,020, Golovin et al.,issued Jul. 30, 1996; U.S. Pat. No. 5,620,810, Golovin et al., issuedApr. 15, 1997; U.S. Pat. No. 5,643,695, Barker et al., issued Jul. 1,1997; U.S. Pat. No. 5,712,059, Barker et al., issued Jan. 27, 1997; U.S.Pat. No. 5,851,504, Barker et al., issued Dec. 22, 1998; U.S. Pat. No.6,020,087, Gao, issued Feb. 1, 2001; U.S. Pat. No. 6,103,419, Saidi etal., issued Aug. 15, 2000; and PCT Application WO 01/24305, Barker etal., published Apr. 5, 2001; all of which are incorporated by referenceherein.

The electrolyte solvent contains a blend of a cyclic ester with analkylene carbonate, an alkyl carbonate, or mixtures thereof. Thealkylene carbonates (cyclic carbonates) have a preferred ring size offrom 5 to 8. The carbon atoms of the ring may be optionally substitutedwith alkyl groups, preferably lower alkyl (C₁-C₆) chains. Examples ofunsubstituted cyclic carbonates are ethylene carbonate (5-memberedring), 1,3-propylene carbonate (6-membered ring), 1,4-butylene carbonate(7-membered ring), and 1,5-pentylene carbonate (8-membered ring).Optionally the rings may be substituted with lower alkyl groups,preferably methyl, ethyl, propyl, or isopropyl groups. Such structuresare well known; examples include a methyl substituted 5-membered ring(also known as 1,2-propylene carbonate, or simply propylene carbonate(PC)), and a dimethyl substituted 5-membered ring carbonate (also knownas 2,3-butylene carbonate) and an ethyl substituted 5-membered ring(also known as 1,2-butylene carbonate or simply butylene carbonate (BC).Other examples include a wide range of methylated, ethylated, andpropylated 5-8 membered ring carbonates. In a preferred embodiment, thefirst component is a 5- or 6-membered ring carbonate. More preferably,the cyclic carbonate has a 5-membered ring. In a particular preferredembodiment, the alkylene carbonate comprises ethylene carbonate.

The alkyl carbonates are preferably C₁-C₆ alkyl, which may beunsubstituted or substituted on one or more carbon atoms with C₁-C₄alkyl. Alkyl carbonates among those useful herein include diethylcarbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC),ethyl methyl carbonate (EMC), and mixtures. DEC is a preferred alkylcarbonate.

The carbonate component of the electrolyte solvent may comprise analkylene carbonate, an alkyl carbonate or mixtures thereof. Preferably,the carbonate is an alkylene carbonate.

The electrolyte solvent also comprises a cyclic ester, preferably alactone. Preferred cyclic esters include those with ring sizes of 4 to7. The carbon atoms in the ring may be optionally substituted with alkylgroups, preferably lower alkyl (C₁-C₆) chains. Examples of unsubstitutedcyclic esters include the 4-membered β-propiolactone (or simplypropiolactone); γ-butyrolactone (5-membered ring), δ-valerolactone(6-membered ring) and ε-caprolactone (7-membered ring). Any of thepositions of the cyclic esters may be optionally substituted, preferablyby methyl, ethyl, propyl, or isopropyl groups. Thus, preferred secondcomponents include one or more solvents selected from the group ofunsubstituted, methylated, ethylated, or propylated lactones selectedfrom the group consisting of propiolacone, butyrolactone, valerolactone,and caprolactone. (It will be appreciated that some of the alkylatedderivatives of one lactone may be named as a different alkylatedderivative of a different core lactone. To illustrate, γ-butyrolactonemethylated on the γ-carbon may be named as γ-valerolactone.)

In a preferred embodiment, the cyclic ester of the second component hasa 5- or a 6-membered ring. Thus, preferred second component solventsinclude one or more compounds selected from y-butyrolactone(gamma-butyrolactone), and δ-valerolactone, as well as methylated,ethylated, and propylated derivatives. Preferably, the cyclic ester hasa 5-membered ring. In a particular preferred embodiment, the secondcomponent cyclic ester comprises γ-butyrolactone.

The preferred two component solvent system contains the two componentsin a weight ratio of from about 1:20 to a ratio of about 20:1. Morepreferably, the ratios range from about 1:10 to about 10:1 and morepreferably from about 1:5 to about 5:1. In a preferred embodiment thecyclic ester is present in a higher amount than the cyclic carbonate.Preferably, at least about 60% (by weight) of the two component systemis made up of the cyclic ester, and preferably about 70% or more. In aparticularly preferred embodiment, the ratio of cyclic ester to cycliccarbonate is about 3 to 1. In one embodiment, the solvent system is madeup essentially of γ-butyrolactone and ethylene carbonate. A preferredsolvent system thus contains about 3 parts by weight γ-butyrolactone andabout 1 part by weight ethylene carbonate. The preferred salt andsolvent are used together in a preferred mixture comprising about 1.5molar LiBF₄ in a solvent comprising about 3 parts γ-butyrolactone andabout 1 part ethylene carbonate by weight.

The solvent optionally comprises additional solvents. Such solventsinclude low molecular weight organic solvents. The optional solvent ispreferably a compatible, relatively non-volatile, aprotic, polarsolvent. Examples of such optional solvents among those useful hereininclude ethers such as diglyme, triglyme, and tetraglyme;dimethylsulfoxide, dioxolane, sulfolane, and mixtures thereof.

A separator allows the migration of ions while still providing aphysical separation of the electric charge between the electrodes, toprevent short-circuiting. The polymeric matrix itself may function as aseparator, providing the physical isolation needed between the anode andcathode. Alternatively, the electrolyte can contain a second oradditional polymeric material to further function as a separator. In apreferred embodiment, the separator prevents damage from elevatedtemperatures within the battery that can occur due to uncontrolledreactions preferably by degrading upon high temperatures to provideinfinite resistance to prevent further uncontrolled reactions.

A separator membrane element is generally polymeric and prepared from acomposition comprising a copolymer. A preferred composition contains acopolymer of about 75% to about 92% vinylidene fluoride with about 8% toabout 25% hexafluoropropylene copolymer (available commercially fromAtochem North America as Kynar FLEX) and an organic solvent plasticizer.Such a copolymer composition is also preferred for the preparation ofthe electrode membrane elements, since subsequent laminate interfacecompatibility is ensured. The plasticizing solvent may be one of thevarious organic compounds commonly used as solvents for electrolytesalts, e.g., propylene carbonate or ethylene carbonate, as well asmixtures of these compounds. Higher-boiling plasticizer compounds suchas dibutyl phthalate, dimethyl phthalate, diethyl phthalate, and trisbutoxyethyl phosphate are preferred. Inorganic filler adjuncts, such asfumed alumina or silanized fumed silica, may be used to enhance thephysical strength and melt viscosity of a separator membrane and, insome compositions, to increase the subsequent level of electrolytesolution absorption. In a non-limiting example, a preferred electrolyteseparator contains about two parts polymer per one part of fumed silica.

A preferred battery comprises a laminated cell structure, comprising ananode layer, a cathode layer, and electrolyte/separator between theanode and cathode layers. The anode and cathode layers comprise acurrent collector. A preferred current collector is a copper collectorfoil, preferably in the form of an open mesh grid. The current collectoris connected to an external current collector tab. Such structures aredisclosed in, for example, U.S. Pat. No. 4,925,752, Fauteux et al,issued May 15, 1990; U.S. Pat. No. 5,011,501, Shackle et al., issuedApr. 30, 1991; and U.S. Pat. No. 5,326,653, Chang, issued Jul. 5, 1994;all of which are incorporated by reference herein. In a batteryembodiment comprising multiple electrochemical cells, the anode tabs arepreferably welded together and connected to a nickel lead. The cathodetabs are similarly welded and connected to a welded lead, whereby eachlead forms the polarized access points for the external load.

A preferred battery comprises a laminated cell structure, comprising ananode layer, a cathode layer, and electrolyte/separator between theanode and cathode layers. The anode and cathode layers comprise acurrent collector. A preferred current collector is a copper collectorfoil, preferably in the form of an open mesh grid. The current collectoris connected to an external current collector tab, for a description oftabs and collectors. Such structures are disclosed in, for example, U.S.Pat. No. 4,925,752, Fauteux et al, issued May 15, 1990; U.S. Pat. No.5,011,501, Shackle et al., issued Apr. 30, 1991; and U.S. Pat. No.5,326,653, Chang, issued Jul. 5, 1994; all of which are incorporated byreference herein. In a battery embodiment comprising multipleelectrochemical cells, the anode tabs are preferably welded together andconnected to a nickel lead. The cathode tabs are similarly welded andconnected to a welded lead, whereby each lead forms the polarized accesspoints for the external load.

Lamination of assembled cell structures is accomplished by conventionalmeans by pressing between metal plates at a temperature of about120-160° C. Subsequent to lamination, the battery cell material may bestored either with the retained plasticizer or as a dry sheet afterextraction of the plasticizer with a selective low-boiling pointsolvent. The plasticizer extraction solvent is not critical, andmethanol or ether are often used.

In a preferred embodiment, an electrode membrane comprising theelectrode active material (e.g., an insertion material such as carbon orgraphite or a insertion compound) is dispersed in a polymeric bindermatrix. The electrolyte/separator film membrane is preferably aplasticized copolymer, comprising a polymeric separator and a suitableelectrolyte for ion transport. The electrolyte/separator is positionedupon the electrode element and is covered with a positive electrodemembrane comprising a composition of a finely divided lithium insertioncompound in a polymeric binder matrix. An aluminum collector foil orgrid completes the assembly. A protective bagging material covers thecell and prevents infiltration of air and moisture.

In another embodiment, a multi-cell battery configuration may beprepared with copper current collector, a negative electrode, anelectrolyte/separator, a positive electrode, and an aluminum currentcollector. Tabs of the current collector elements form respectiveterminals for the battery structure.

In a preferred embodiment of a lithium-ion battery, a current collectorlayer of aluminum foil or grid is overlaid with a positive electrodefilm, or membrane, separately prepared as a coated layer of a dispersionof insertion electrode composition. This is preferably an insertioncompound such as the active material of the present invention in powderform in a copolymer matrix solution, which is dried to form the positiveelectrode. An electrolyte/separator membrane is formed as a driedcoating of a composition comprising a solution containing VdF:HFPcopolymer and a plasticizer solvent is then overlaid on the positiveelectrode film. A negative electrode membrane formed as a dried coatingof a powdered carbon or other negative electrode material dispersion ina VdF:HFP copolymer matrix solution is similarly overlaid on theseparator membrane layer. A copper current collector foil or grid islaid upon the negative electrode layer to complete the cell assembly.Therefore, the VdF:HFP copolymer composition is used as a binder in allof the major cell components, positive electrode film, negativeelectrode film, and electrolyte/separator membrane. The assembledcomponents are then heated under pressure to achieve heat-fusion bondingbetween the plasticized copolymer matrix electrode and electrolytecomponents, and to the collector grids, to thereby form an effectivelaminate of cell elements. This produces an essentially unitary andflexible battery cell structure.

Cells comprising electrodes, electrolytes and other materials amongthose useful herein are described in the following documents, all ofwhich are incorporated by reference herein: U.S. Pat. No. 4,668,595,Yoshino et al., issued May 26, 1987; U.S. Pat. No. 4,792,504, Schwab etal., issued Dec. 20, 1988; U.S. Pat. No. 4,830,939, Lee et al., issuedMay 16, 1989; U.S. Pat. No. 4,935,317, Fauteaux et al., issued Jun. 19,1980; U.S. Pat. No. 4,990,413, Lee et al., issued Feb. 5, 1991; U.S.Pat. No. 5,037,712, Shackle et al., issued Aug. 6, 1991; U.S. Pat. No.5,262,253, Golovin, issued Nov. 16, 1993; U.S. Pat. No. 5,300,373,Shackle, issued Apr. 5, 1994; U.S. Pat. No. 5,399,447, Chaloner-Gill, etal., issued Mar. 21, 1995; U.S. Pat. No. 5,411,820, Chaloner-Gill,issued May 2, 1995; U.S. Pat. No. 5,435,054, Tonder et al., issued Jul.25, 1995; U.S. Pat. No. 5,463,179, Chaloner-Gill et al., issued Oct. 31,1995; U.S. Pat. No. 5,482,795, Chaloner-Gill., issued Jan. 9, 1996; U.S.Pat. No. 5,660,948, Barker, issued Sep. 16, 1995; and U.S. Pat. No.6,306,215, Larkin, issued Oct. 23, 2001. A preferred electrolyte matrixcomprises organic polymers, including VdF:HFP. Examples of casting,lamination and formation of cells using VdF:HFP are as described in U.S.Pat. No. 5,418,091, Gozdz et al., issued May 23, 1995; U.S. Pat. No.5,460,904, Gozdz et al., issued Oct. 24, 1995; U.S. Pat. No. 5,456,000,Gozdz et al., issued Oct. 10, 1995; and U.S. Pat. No. 5,540,741, Gozdzet al., issued Jul. 30,1996; all of which are incorporated by referenceherein.

The electrochemical cell architecture is typically governed by theelectrolyte phase. A liquid electrolyte battery generally has acylindrical shape, with a thick protective cover to prevent leakage ofthe internal liquid. Liquid electrolyte batteries tend to be bulkierrelative to solid electrolyte batteries due to the liquid phase andextensive sealed cover. A solid electrolyte battery, is capable ofminiaturization, and can be shaped into a thin film. This capabilityallows for a much greater flexibility when shaping the battery andconfiguring the receiving apparatus. The solid state polymer electrolytecells can form flat sheets or prismatic (rectangular) packages, whichcan be modified to fit into the existing void spaces remaining inelectronic devices during the design phase.

The following non-limiting examples illustrate the compositions andmethods of the present invention.

EXAMPLE 1

An electrode active material of formulaLi_(1.025)Co_(0.9)Al_(0.025)Mg_(0.05)PO₄, is made as follows. Thefollowing sources of Li, Co, Al, Mg, and phosphate are providedcontaining the respective elements in a molar ratio of1.025:0.9:0.025:0.05:1. (1) 0.05125 moles Li₂CO₃ (mol. wt. 73.88 g/mol)3.8 g (2) 0.03 moles Co₃O₄ (240.8 g/mol) 7.2 g (3) 0.0025 motes Al(OH)₃(78 g/mol) 0.195 g (4) 0.005 moles Mg(OH)₂ (58 g/mol) 0.29 g (5) 0.1moles (NH₄)₂HPO₄ (132 g/mol) 13.2 g (6) 0.2 moles elemental carbon (12g/mol) (>100% excess) 2.4 g

The above starting materials are combined and ball milled to mix theparticles. Thereafter, the particle mixture is pelletized. Thepelletized mixture is heated for 4-20 hours at 750° C. in an oven in anargon atmosphere. The sample is removed from the oven and cooled. Anx-ray diffraction pattern shows that the material has an olivine typecrystal structure. An electrode is made with 80% of the active material,10% of Super P conductive carbon, and 10% poly vinylidene difluoride. Acell with that electrode as cathode and lithium metal as anode isconstructed with an electrolyte comprising 1 M LiBF₄ dissolved in a 3:1by weight mixture of γ-butyrolactone:ethylene carbonate. The activematerial exhibits a reversible capacity over 140 mAhg-1.

EXAMPLE 2

An electrode active material of formulaLi_(1.025)Co_(0.85)Fe_(0.05)Al_(0.025)Mg_(0.05)PO₄(LiCo_(0.85)Fe_(0.05)Al_(0.025)Mg_(0.05)Li_(0.025)PO₄) is made asfollows. The following sources of Li, Co, Fe, Al, Mg, and phosphate areprovided containing the respective elements in a molar ratio of1.025:0.85:0.05:0.025:0.05:1. (1) 0.05125 moles Li₂CO₃ (mol. wt. 73.88g/mol) 3.8 g (2) 0.02833 moles Co₃O₄ (240.8 g/mol) 6.82 g (3) 0.0025moles Fe₂O₃ (159.7 g/mol) 0.4 g (4) 0.0025 moles Al(OH)₃ (78 g/mol)0.195 g (5) 0.005 moles Mg(OH)₂ (58 g/mol) 0.29 g (6) 0.1 moles(NH₄)₂HPO₄ (132 g/mol) 13.2 g (7) 0.2 moles elemental carbon (12 g/mol)(>100% excess) 2.4 g

The above starting materials are combined and ball milled to mix theparticles. Thereafter, the particle mixture is pelletized. Thepelletized mixture is heated for 4-20 hours at 750° C. in an oven in anargon atmosphere. The sample is removed from the oven and cooled. Anx-ray diffraction pattern shows that the material has an olivine typecrystal structure. An electrode is made with 80% of the active material,10% of Super P conductive carbon, and 10% poly vinylidene difluoride. Acell with that electrode as cathode and a carbon intercalation anode isconstructed with an electrolyte comprising 1 M LiPF₆ dissolved in a2:1:1 by weight mixture of γ-butyrolactone:ethylene carbonate:dimethylcarbonate.

EXAMPLE 3

An electrode active material of the formulaLi_(1.025)Co_(0.8)Fe_(0.1)Al_(0.025)Mg_(0.05)PO₄(LiCo_(0.8)Fe_(0.1)Al_(0.025)Mg_(0.05)Li_(0.025)PO₄) is made as follows.The following sources of Li, Co, Fe, Al, Mg, and phosphate are providedcontaining the respective elements in a molar ratio of 1.025:0.8:0.1:0.025:0.05:1. (1) 0.05125 moles Li₂CO₃ (mol. wt. 73.88 g/mol) 3.8 g (2)0.02667 moles Co₃O₄ (240.8 g/mol) 6.42 g (3) 0.005 moles Fe₂O₃ (159.7g/mol) 0.8 g (4) 0.0025 moles Al(OH)₃ (78 g/mol) 0.195 g (5) 0.005 molesMg(OH)₂ (58 g/mol) 0.29 g (6) 0.1 moles (NH₄)₂HPO₄ (132 g/mol) 13.2 g(7) 0.2 moles elemental carbon (12 g/mol) (>100% excess) 2.4 g

The above starting materials are combined and ball milled to mix theparticles. Thereafter, the particle mixture is pelletized. Thepelletized mixture is heated for 4-20 hours at 750° C. in an oven in anargon atmosphere. The sample is removed from the oven and cooled. Anx-ray diffraction pattern shows that the material has an olivine typecrystal structure. An electrode is made with 80% of the active material,10% of Super P conductive carbon, and 10% poly vinylidene difluoride. Acell with that electrode as cathode and a carbon intercalation anode isconstructed with an electrolyte comprising 1 M LiPF₆ dissolved in a 3:1by weight mixture of γ-butyrolactone:ethylene carbonate.

EXAMPLE 4

An electrode active material of the formulaLiCo_(0.8)Fe_(0.0)5Al_(0.1)Mg_(0.05)(PO₄)_(0.9)(SiO₄)_(0.1) is made asfollowing sources Li, Co, Fe, Al, Mg, phosphate, and silicate areprovided containing the respective elements in a molar ratio of1:0.8:0.05:0.1 :0.05:0.9:0.1. (1) 0.05 moles Li₂CO₃ (mol. wt. 73.88g/mol) 3.7 g (2) 0.08 moles CoCO₃ (118.9 g/mol) 9.5 g (3) 0.0025 molesFe₂O₃ (159.7 g/mol) 0.4 g (4) 0.0025 moles Al(OH)₃ (78 g/mol) 0.195 g(5) 0.005 moles Mg(OH)₂ (58 g/mol) 0.29 g (6) 0.09 moles (NH₄)₂HPO₄ (132g/mol) 11.9 g (7) 0.01 moles SiO₂ (60.1 g/mol) 0.6 g (8) 0.2 moleselemental carbon (12 g/mol) (excess) 2.4 g

The above amounts of starting materials are combined and ball milled tomix the particles. Note that the reducing carbon is present inapproximately a 40-fold excess, relative to the 0.05 moles of iron inthe iron III oxide to be reduced. Thereafter, the particle mixture ispelletized. The pelletized mixture is heated for 4-20 hours at 750° C.in an oven in an argon atmosphere. The sample is removed from the ovenand cooled. An electrode is made with 80% of the active material, 10% ofSuper P conductive carbon, and 10% polyvinylidene difluoride. A cellwith that electrode as cathode and a carbon intercalation anode isconstructed with an electrolyte comprising 1 M LiBF₄ dissolved in 3:1 byweight mixture of γ-butyrolactone:ethylene carbonate.

EXAMPLE 5

An electrode active material of the formulaLiCo_(0.8)Fe_(0.1)Al_(0.025)Mg_(0.05)PO_(3.975)F_(0.025) is made asfollows. The following containing Li, Co, Fe, Al, Mg, phosphate, andfluoride are provided containing the respective elements in a molarratio of 1.0:0.8:0.1:0.025:0.05:1.0:0.025. (1) 0.05 moles Li₂CO₃ (mol.wt. 73.88 g/mol), 3.7 g 0.1 mol Li (2) 0.02667 moles Co₃O₄ (240.8g/mol), 6.42 g 0.08 mol Co (3) 0.005 moles Fe₂O₃ (159.7 g/mol), 0.8 g0.01 mol Fe (4) 0.0025 moles Al(OH)₃ (78 g/mol), 0.195 g 0.0025 mol Al(5) 0.005 moles Mg(OH)₂ (58 g/mol), 0.29 g 0.005 mol Mg (6) 0.1 moles(NH₄)₂HPO₄ (132 g/mol), 13.2 g 0.1 mol phosphate (7) 0.00125 molesNH₄HF₂ (57 g/mol), 0.071 g 0.0025 mol F (8) 0.2 moles elemental carbon(12 g/mol) 2.4 g (>100% excess)

The above starting materials are combined and ball milled to mix theparticles. Thereafter, the particle mixture is pelletized. Thepelletized mixture is heated for 4-20 hours at 750° C. in an oven in anargon atmosphere. The sample is removed from the oven and cooled. Anx-ray diffraction pattern shows that the material has an olivine typecrystal structure. An electrode is made with 80% of the active material,10% of Super P conductive carbon, and 10% polyvinylidene difluoride. Acell with that electrode as cathode and a carbon intercalation anode isconstructed with an electrolyte comprising 1 M LiBF₄ dissolved in a 3:1mixture by weight of γ-butyrolactone:propylene carbonate.

EXAMPLE 6

An electrode active material of the formula LiFe_(0.9)Mg_(0.1)PO₄is madeaccording to the following reaction scheme.0.50 Li₂CO₃+0.45 Fe₂O₃+0.10 Mg(OH)₂+(NH₄)₂HPO4+0.45 C→LiFe_(0.9)Mg_(0.1)PO₄+0.50 CO₂+0.45 CO+2.0 NH₃+1.6 H₂O

A mixture of 36.95 g (0.50 mol) of Li₂CO₃, 71.86 g (0.45 mol) of Fe₂O₃,5.83 g (0.10 mol) of 0.10 Mg(OH)₂, 132.06 g (1.0 mol) of (NH₄)₂HPO₄, and10.8 g (0.90 g-mol, 100% excess) of carbon is made, using a mortar andpestle. The mixture is pelletized, and transferred to atemperature-controlled tube furnace equipped with an argon gas flow. Themixture is heated at a ramp rate of about 2° C./minute to an ultimatetemperature of about 750° C. in the inert atmosphere and maintained atthis temperature for about 8 hours. The product is then cooled toambient temperature (about 22° C.). An electrode is made with 80% of theactive material, 10% of Super P conductive carbon, and 10%polyvinylidene difluoride. A cell with that electrode as cathode and acarbon intercalation anode is constructed with an electrolyte comprising1M LiBF₄ dissolved in a 4:1 mixture by weight ofδ-valerolactone:ethylene carbonate.

EXAMPLE 7

An electrode active material comprisingLi_(1.25)Fe_(0.9)Mg_(0.1)PO₄F_(0.25) is made according to the followingreaction scheme.LiFe_(0.9)Mg_(0.1)PO₄+d LiF→Li_(1+d)Fe_(0.9)Mg_(0.1)PO₄F_(d)

For d equal to 0.25, 1.082 grams of LiFe_(0.9)Mg_(0.1)PO₄ (made as inExample 6) and 0.044 grams of LiF are premixed and pelletized,transferred to an oven and heated to an ultimate temperature of 700° C.and maintained for 15 minutes at this temperature. The sample is cooledand removed from the oven. Almost no weight loss is recorded for thereaction, consistent with full incorporation of the lithium fluorideinto the phosphate structure to make an active material of formulaLi_(1.25)Fe_(0.9)Mg_(0.1)PO₄F_(0.25). An electrode is made with 80% ofthe active material, 10% of Super P conductive carbon, and 10%polyvinylidene difluoride. A cell with that electrode as cathode and acarbon intercalation anode is constructed with an electrolyte comprising1M LiBF₄ dissolved in a 3:1 mixture by weight ofy-butyrolactone:ethylene carbonate.

EXAMPLE 8

An electrode active material comprising NaVPO₄F is made according to thefollowing reaction scheme.0.5Na₂CO₃+NH₄F+VPO₄→NaVPO₄F+NH₃+0.5CO₂+0.5H₂O

1.23 grams of VPO₄, 0.31 grams of NH₄F, and 0.45 grams Na₂CO₃ arepremixed with approximately 20 milliliters of deionized water andtransferred and sealed in a Parr Model 4744 acid digestion bomb, whichis a Teflon lined stainless steel reaction vessel. The bomb is placed inan oven and heated to an ultimate temperature of 250° C. and maintainedat this temperature for forty-eight hours. The sample is cooled to roomtemperature and removed for analysis. The sample is washed repeatedlywith the deionized water to remove unreacted impurities and thereafteris dried in an argon atmosphere at 250° C. for an hour.

EXAMPLE 9

An electrode active material comprisingLi_(2.025)Co_(0.9)Al_(0.025)Mg_(0.05)PO₄F is made as follows. (ThisExample shows the synthesis of a mixed metal active material containinglithium and three different metals, with two metals in a +2 and onemetal in a +3 oxidation state). For A=Li, a=2.025, M¹=Co, M²=Al, andM³=Mg, the reaction proceeds according to the following scheme.0.5125 Li₂CO₃+0.3 Co₃(PO₄)₂.8H₂O+0.0125 Al₂O₃+0.05 Mg(OH)₂+LiF+0.4 NH₄H₂PO₄ Li_(2.025)Co_(0.9)Al_(0.025)Mg_(0.05)PO₄F+0.5125 CO₂+0.4 NH₃+8.9 H₂O.

Powdered starting materials are provided in the molar ratios indicated,mixed, pelletized, and heated in an oven at 750° C. for four hours toproduce a reaction product. An electrode is made with 80% of the activematerial, 10% of Super P conductive carbon, and 10% polyvinylidenedifluoride. A cell with that electrode as cathode and a carbonintercalation anode is constructed with an electrolyte comprising 1MLiBF₄ dissolved in a 3:2 mixture by weight of β-propiolactone:ethylenecarbonate.

EXAMPLE 10

An electrode active material comprising Li₆V₂(PO₄)₃F is synthesizedaccording to the equation3 C+2.5 Li₂CO₃+V₂O₅+LiF+3NH₄H₂PO₄→Li₆V₂(PO₄)₃F+2.5CO₂+3NH₃+4.5H₂O+3CO.

The equation presupposes that the carbothermal reaction proceeds withproduction of carbon monoxide. The carbon is provided in excess, in thiscase to reduce the vanadium +5 species all the way down to its lowestoxidation of +2. It is appreciated in the reaction scheme that such areduction is possible because there is enough lithium in the reactionscheme that lithium is incorporated into the reaction product in anamount sufficient to neutralize the [(PO₄)₃F]¹⁰⁻ group of the activematerial. An electrode is made with 80% of the active material, 10% ofSuper P conductive carbon, and 10% polyvinylidene difluoride. A cellwith that electrode as cathode and a carbon intercalation anode isconstructed with an electrolyte comprising 1M LiBF₄ dissolved in a 3:1mixture by weight of γ-butyrolactone:ethylene carbonate.

The examples and other embodiments described herein are exemplary andnot intended to be limiting in describing the full scope of compositionsand methods of this invention. Equivalent changes, modifications andvariations of specific embodiments, materials, compositions and methodsmay be made within the scope of the present invention, withsubstantially similar results.

1. A battery, comprising: (a) a first electrode comprising an activematerial of the formula:Li_(a)Co_(e)Fe_(f)M¹ _(g)M² _(h)M³ _(i)XY₄, wherein: (i) 0<a≦2,e>0, andf>0; (ii) M¹ is one or more transition metals, where g≧0; (iii) M² isone or more +2 oxidation state non-transition metals, where h≧0; (iv) M³is one or more +3 oxidation state non-transition metals, where i≧0; and(v) XY₄ is selected from the group consisting of X′O_(4-x)Y′_(x),X′O_(4-y)Y′_(2y), X″S₄, and mixtures thereof, where X′ is selected fromthe group consisting of P, As, Sb, Si, Ge, V, S, and mixtures thereof;X″ is selected from the group consisting of P, As, Sb, Si, Ge, V andmixtures thereof; Y′ is selected from the group consisting of halogen,S, N, and mixtures thereof; 0≦x≦3; and 0<y≦2; and (vi) wherein(e+f+g+h+i)<2, and M¹, M², M³, XY₄, a, e, f, g, h, i, x, and y areselected so as to maintain electroneutrality of said compound; and (b) asecond electrode which is a counter-electrode to said first electrode;and (c) an electrolyte comprising an electrolyte salt, a cyclic esterand a carbonate selected from the group consisting of alkyl carbonates,alkylene carbonates, and mixtures thereof.
 2. The battery according toclaim 1, wherein 0.8≦(e+f+g+h+i)≦1.2.
 3. The battery according to claim2, wherein 0.9≦(e+f+g+h+i)≦1.
 4. The battery according to claim 2,wherein e≧0.5.
 5. The battery according to claim 4, wherein e≧0.8. 6.The battery according to claim 2, wherein 0.01≦f≦0.5.
 7. The batteryaccording to claim 6, wherein 0.05≦f≦0.15.
 8. The battery according toclaim 3, wherein 0.01≦g≦0.5.
 9. The battery according to claim 8,wherein 0.05≦g≦0.2.
 10. The battery according to claim 8, wherein M¹ isselected from the group consisting of Ti, V, Cr, Mn, Ni, Cu and mixturesthereof.
 11. The battery according to claim 10, wherein M¹ is selectedfrom the group consisting of Mn, Ti, and mixtures thereof.
 12. Thebattery according to claim 2, wherein (h+i)>0.
 13. The battery accordingto claim 12, wherein 0.01≦(h+i)≦0.5.
 14. The battery according to claim13, wherein 0.02≦(h+i)≦0.3.
 15. The battery according to claim 13,wherein 0.01≦h≦0.2.
 16. The battery according to claim 15, wherein0.01≦h≦0.1.
 17. The battery according to claim 15, wherein M² isselected from the group consisting of Be, Mg, Ca, Sr, Ba, and mixturesthereof.
 18. The battery according to claim 17, wherein M² is Mg. 19.The battery according to claim 13, wherein 0.01≦i≦0.2.
 20. The batteryaccording to claim 19, wherein 0.01≦i≦0.1.
 21. The battery according toclaim 19, wherein M³ is selected from the group consisting of B, Al, Ga,In and mixtures thereof.
 22. The battery according to claim 21, whereinM³ is Al.
 23. The battery according to claim 1, wherein XY₄ is PO₄. 24.The battery according to claim 23, wherein e≧0.8, and 0.05≦f≦0.15. 25.The battery according to claim 24, wherein 0.01≦h≦0.1.
 26. The batteryaccording to claim 25, wherein M² is selected from the group consistingof Be, Mg, Ca, Sr, Ba, and mixtures thereof.
 27. The battery accordingto claim 24, wherein 0.01≦i≦0.1.
 28. The battery according to claim 27,wherein M³ is Al.
 29. The battery according to claim 1, wherein XY₄ isPO_(4-x)F_(x), and 0<x≦1.
 30. The battery according to claim 29, wherein0.01≦x≦0.05.
 31. The battery according to claim 29, wherein e≧0.8, and0.05≦f≦0.15.
 32. The battery according to claim 31, wherein 0.01≦h≦0.1.33. The battery according to claim 32, wherein M² is selected from thegroup consisting of Be, Mg, Ca, Sr, Ba, and mixtures thereof.
 34. Thebattery according to claim 31, wherein 0.01≦i≦0.1.
 35. The batteryaccording to claim 34, wherein M³ is Al.
 36. The battery according toclaim 1, wherein said carbonate comprises an alkylene carbonate having aring size of from 5 to 8 atoms and is unsubstituted or substituted withlower alkyl on one or more carbon atoms.
 37. The battery according toclaim 36, wherein said alkylene carbonate is selected from the groupconsisting of ethylene carbonate, 1,3-propylene carbonate, 1,4-butylenecarbonate, 1,5-pentylene carbonate, 1,2-propylene carbonate, 2,3butylenecarbonate, 1,2-butylene carbonate, and mixtures thereof.
 38. The batteryaccording to claim 37, wherein said alkylene carbonate is ethylenecarbonate.
 39. The battery according to claim 1, wherein said carbonatecomprises a C₁-C₆ alkyl carbonate which is unsubstituted or substitutedwith C₁-C₄ alkyl on one or more carbon atoms.
 40. The battery accordingto claim 39, wherein said alkyl carbonate is selected from the groupconsisting of diethyl carbonate, ethyl methyl carbonate, dimethylcarbonate, and mixtures thereof.
 41. The battery according to claim 39,wherein said cyclic ester has a ring size of from 4 to 7 atoms, and isunsubstituted or substituted on one or more carbon atoms with a loweralkyl group.
 42. The battery according to claim 41, wherein said cyclicester is selected from the group consisting of substituted orunsubstituted β-propiolactone; substituted or unsubstitutedγ-butyrolactone, substituted or unsubstituted δ-valerolactone,substituted or unsubstituted ε-caprolactone, and mixtures thereof. 43.The battery according to claim 41, wherein said cyclic ester isγ-butyrolactone.
 44. The battery according to claim 1, wherein saidelectrolyte salt is a lithium salt selected from the group consisting ofLiAsF₆, LiPF₆, LiClO₄, LiB(C₆H₅)₄, LiAlCl₄, LiBr, LiBF₄, LiSO₃CF₃,LiN(SO₂CF₃)₂, LiN(SO₂C₂F₅)₂, and mixtures thereof.
 45. The batteryaccording to claim 44, wherein said salt is LiBF₄.
 46. The batteryaccording to claim 1, wherein said cyclic ester comprises at least about60% of said electrolyte, and the weight ratio of said cyclic ester tosaid alkylene carbonate is from about 1:1 to about 5:1.
 47. The batteryaccording to claim 46, wherein said weight ratio is about 3:1.
 48. Thebattery of claim 1, wherein said first electrode is a cathode, and saidsecond electrode is an insertion anode.
 49. The battery of claim 48,wherein said second electrode comprises a material selected from thegroup consisting of metal oxides, metal chalcogenides, carbon, graphite,and mixtures thereof.